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PD/IClear/Help

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Filename: PD/IClear/Help
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File size: 1A63 bytes
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Exec address: 0000
File contents
                               IClear Module
                               ====== ======

                               by Martyn Fox

This software is Public Domain. It may be freely copied and distributed,
including distribution by magazine discs, PD libraries, bulletin boards
etc., provided the following conditions are adhered to:

1. No charge is made other than to cover the reasonable cost of duplication
and distribution.

2. No alteration is made to either the software or this text file.

3. This text file accompanies all copies of the software.

Please note that this module will only work with RISC OS 3 or later.

IClear is a module which makes it easier to delete text from a writable
icon. Under RISC OS, to replace the text in such an icon with new text, you
first have to either delete all the characters of the old text or press
Ctrl-U to clear it. This can be a nuisance, especially if you have just
selected the icon with the mouse, as you first have to transfer to the
keyboard, then press Ctrl-U before you can type in your new text.

With IClear running, simply double-click on the writable icon, using either
Select or Adjust. The icon will be inverted, which usually means that it
will turn black with white text. As soon as you press a key, the text in the
icon will vanish, to be replaced with the character that you typed. If you
change your mind after inverting the icon and decide you want to keep your
existing text, a further click with any mouse button anywhere on the screen
will de-invert the icon and put things back to normal.

This software will work with writable icons (button type 15) and also
draggable writable icons (button type 14) but not with writable menu items.

                             Programming Notes
                             =========== =====

The module intercepts the MouseV and InsV vectors to detect calls to
OS_Mouse and keypresses. OS_Mouse calls are first passed onto the SWI
routine and processed on exit.

Because RISC OS will not automatically detect a double-click over a writable
icon, the module has to do the job itself. This involves checking the time
interval since the previous click, selecting the 'double-arrow' pointer
sprite, checking which button was pressed and monitoring the mouse position.

Rather than put too much code into a vector intercept routine, the software
just sets one of two callbacks, depending on the time interval since the
previous click. The callback routine is called by RISC OS as soon as it is
not busy. The first of these callbacks handles a single click. It first
checks to see if the module has a record of an inverted icon and, if so,
takes steps to clear it. It then stores a record of which button was pressed
and checks the icon type. If the click was over a writable icon, it stores
the mouse position and redefines mouse pointer 1 sprite as ptr_double.

N.B. There appears to be no way of reading which sprite is used by a
particular pointer number. The PRM though says that only RISC OS should use
pointer 1, so this pointer should presumably always use the ptr_default
arrow sprite. The module assumes this and always replaces ptr_double with
ptr_default at the end of the period during which it checks for a second
click.

The module then sets a call-after, which is an instruction to RISC OS to
call a routine after a certain length of time. It also calls OS_CallEvery to
arrange for a call every 10 centiseconds to a routine which checks the mouse
position and cancels the double-click monitoring if the mouse is moved more
than a certain amount.

N.B. Although the normal double-click time limit and permitted mouse
movement can be configured, there appears to be no way of reading their
values, other than the unreliable method of checking CMOS RAM locations,
which could change between different versions of RISC OS. This module uses
the default configuration values of 1 second maximum between clicks and a
maximum mouse movement of 10 OS units (it checks for either 10 horizontal or
10 vertical units of movement). These values are fixed in this version of
the module. If there is a demand for the ability to alter these values, I
will endeavour to include a couple of SWIs and/or star commands in a later
version.

If either a second key is pressed or the mouse is moved before the
call-after has timed out, the call-after and call-every are cancelled and a
second callback is used. This routine checks that the same key has been
pressed as previously, sets a flag and takes steps to invert the icon.

Although any icon can be inverted or de-inverted by means of a call to
Wimp_SetIconState, the procedure is not that simple. This SWI may only be
called while the application which owns the icon is the currently active
task. If we simply call it when the mouse is clicked, this may not be the
case, especially if several multi-tasking applications are running at the
same time. We have to send a message to the task but we cannot, of course,
rewrite its software.

The solution is to use a filter. We could use a pre-filter, which is called
just before Wimp_Poll is executed, or a post-filter which is called on
return from Wimp_Poll. In this case, we use the latter. The technique is to
send a unique message to the task which our filter will intercept and
recognise, telling it to invert or de-invert the required icon.

We could send a message, using reason code 17 or 18, but we would have to
find a message action code that is not used for anything else, which would
present problems. It is also permissible for a task to mask out these reason
codes, which would prevent our message getting through. So that this cannot
happen, the module sends a message with reason code 2, which usually means
'open window request'. This reason code is not supposed to be masked out
when calling Wimp_Poll. Our message sends R1+0 as zero and R1+4 as
&726C4349, which is the ASCII code for 'IClr'. This corresponds to a request
to open the window whose handle is zero, with a minimum x coordinate of
&726C4349 - a most unlikely state of affairs in any other situation! The
third word in the block is zero to clear the icon or 1 to invert it. The
filter is set to handle only reason code 2. If it receives the exact state
of affairs as described, it either inverts or clears the icon and exits
without passing the call onto the application.

If a key is pressed while the inverted icon flag is set, the routine (again
by means of a callback) sends a message to clear the icon, then sends the
keypress character, preceded by a Ctrl-U to delete the text.

The module incorporates a self-checking routine to detect corruption by
viruses.

Please send all comments and suggestions to:

M.P. Fox,
31 Pierson Road,
Windsor,
Berks. SL4 5RE
00000000  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
00000010  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 49  |               I|
00000020  43 6c 65 61 72 20 4d 6f  64 75 6c 65 0a 20 20 20  |Clear Module.   |
00000030  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
00000040  20 20 20 20 20 20 20 20  20 20 20 20 3d 3d 3d 3d  |            ====|
00000050  3d 3d 20 3d 3d 3d 3d 3d  3d 0a 0a 20 20 20 20 20  |== ======..     |
00000060  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
00000070  20 20 20 20 20 20 20 20  20 20 62 79 20 4d 61 72  |          by Mar|
00000080  74 79 6e 20 46 6f 78 0a  0a 54 68 69 73 20 73 6f  |tyn Fox..This so|
00000090  66 74 77 61 72 65 20 69  73 20 50 75 62 6c 69 63  |ftware is Public|
000000a0  20 44 6f 6d 61 69 6e 2e  20 49 74 20 6d 61 79 20  | Domain. It may |
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000000c0  20 61 6e 64 20 64 69 73  74 72 69 62 75 74 65 64  | and distributed|
000000d0  2c 0a 69 6e 63 6c 75 64  69 6e 67 20 64 69 73 74  |,.including dist|
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00000230  0a 50 6c 65 61 73 65 20  6e 6f 74 65 20 74 68 61  |.Please note tha|
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000002c0  63 6f 6e 2e 20 55 6e 64  65 72 20 52 49 53 43 20  |con. Under RISC |
000002d0  4f 53 2c 20 74 6f 20 72  65 70 6c 61 63 65 20 74  |OS, to replace t|
000002e0  68 65 20 74 65 78 74 20  69 6e 20 73 75 63 68 20  |he text in such |
000002f0  61 6e 20 69 63 6f 6e 20  77 69 74 68 20 6e 65 77  |an icon with new|
00000300  20 74 65 78 74 2c 20 79  6f 75 0a 66 69 72 73 74  | text, you.first|
00000310  20 68 61 76 65 20 74 6f  20 65 69 74 68 65 72 20  | have to either |
00000320  64 65 6c 65 74 65 20 61  6c 6c 20 74 68 65 20 63  |delete all the c|
00000330  68 61 72 61 63 74 65 72  73 20 6f 66 20 74 68 65  |haracters of the|
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00000380  73 70 65 63 69 61 6c 6c  79 20 69 66 20 79 6f 75  |specially if you|
00000390  20 68 61 76 65 20 6a 75  73 74 0a 73 65 6c 65 63  | have just.selec|
000003a0  74 65 64 20 74 68 65 20  69 63 6f 6e 20 77 69 74  |ted the icon wit|
000003b0  68 20 74 68 65 20 6d 6f  75 73 65 2c 20 61 73 20  |h the mouse, as |
000003c0  79 6f 75 20 66 69 72 73  74 20 68 61 76 65 20 74  |you first have t|
000003d0  6f 20 74 72 61 6e 73 66  65 72 20 74 6f 20 74 68  |o transfer to th|
000003e0  65 0a 6b 65 79 62 6f 61  72 64 2c 20 74 68 65 6e  |e.keyboard, then|
000003f0  20 70 72 65 73 73 20 43  74 72 6c 2d 55 20 62 65  | press Ctrl-U be|
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000004f0  61 20 6b 65 79 2c 20 74  68 65 20 74 65 78 74 20  |a key, the text |
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00000680  28 62 75 74 74 6f 6e 20  74 79 70 65 20 31 34 29  |(button type 14)|
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000006c0  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
000006d0  20 50 72 6f 67 72 61 6d  6d 69 6e 67 20 4e 6f 74  | Programming Not|
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00000700  3d 3d 3d 3d 3d 3d 3d 3d  3d 3d 3d 20 3d 3d 3d 3d  |=========== ====|
00000710  3d 0a 0a 54 68 65 20 6d  6f 64 75 6c 65 20 69 6e  |=..The module in|
00000720  74 65 72 63 65 70 74 73  20 74 68 65 20 4d 6f 75  |tercepts the Mou|
00000730  73 65 56 20 61 6e 64 20  49 6e 73 56 20 76 65 63  |seV and InsV vec|
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00000970  74 65 72 76 61 6c 20 73  69 6e 63 65 20 74 68 65  |terval since the|
00000980  0a 70 72 65 76 69 6f 75  73 20 63 6c 69 63 6b 2e  |.previous click.|
00000990  20 54 68 65 20 63 61 6c  6c 62 61 63 6b 20 72 6f  | The callback ro|
000009a0  75 74 69 6e 65 20 69 73  20 63 61 6c 6c 65 64 20  |utine is called |
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000009f0  6b 73 20 68 61 6e 64 6c  65 73 20 61 20 73 69 6e  |ks handles a sin|
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00000aa0  73 20 70 72 65 73 73 65  64 0a 61 6e 64 20 63 68  |s pressed.and ch|
00000ab0  65 63 6b 73 20 74 68 65  20 69 63 6f 6e 20 74 79  |ecks the icon ty|
00000ac0  70 65 2e 20 49 66 20 74  68 65 20 63 6c 69 63 6b  |pe. If the click|
00000ad0  20 77 61 73 20 6f 76 65  72 20 61 20 77 72 69 74  | was over a writ|
00000ae0  61 62 6c 65 20 69 63 6f  6e 2c 20 69 74 20 73 74  |able icon, it st|
00000af0  6f 72 65 73 0a 74 68 65  20 6d 6f 75 73 65 20 70  |ores.the mouse p|
00000b00  6f 73 69 74 69 6f 6e 20  61 6e 64 20 72 65 64 65  |osition and rede|
00000b10  66 69 6e 65 73 20 6d 6f  75 73 65 20 70 6f 69 6e  |fines mouse poin|
00000b20  74 65 72 20 31 20 73 70  72 69 74 65 20 61 73 20  |ter 1 sprite as |
00000b30  70 74 72 5f 64 6f 75 62  6c 65 2e 0a 0a 4e 2e 42  |ptr_double...N.B|
00000b40  2e 20 54 68 65 72 65 20  61 70 70 65 61 72 73 20  |. There appears |
00000b50  74 6f 20 62 65 20 6e 6f  20 77 61 79 20 6f 66 20  |to be no way of |
00000b60  72 65 61 64 69 6e 67 20  77 68 69 63 68 20 73 70  |reading which sp|
00000b70  72 69 74 65 20 69 73 20  75 73 65 64 20 62 79 20  |rite is used by |
00000b80  61 0a 70 61 72 74 69 63  75 6c 61 72 20 70 6f 69  |a.particular poi|
00000b90  6e 74 65 72 20 6e 75 6d  62 65 72 2e 20 54 68 65  |nter number. The|
00000ba0  20 50 52 4d 20 74 68 6f  75 67 68 20 73 61 79 73  | PRM though says|
00000bb0  20 74 68 61 74 20 6f 6e  6c 79 20 52 49 53 43 20  | that only RISC |
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00000c60  70 74 72 5f 64 65 66 61  75 6c 74 20 61 74 20 74  |ptr_default at t|
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00000ca0  61 20 73 65 63 6f 6e 64  0a 63 6c 69 63 6b 2e 0a  |a second.click..|
00000cb0  0a 54 68 65 20 6d 6f 64  75 6c 65 20 74 68 65 6e  |.The module then|
00000cc0  20 73 65 74 73 20 61 20  63 61 6c 6c 2d 61 66 74  | sets a call-aft|
00000cd0  65 72 2c 20 77 68 69 63  68 20 69 73 20 61 6e 20  |er, which is an |
00000ce0  69 6e 73 74 72 75 63 74  69 6f 6e 20 74 6f 20 52  |instruction to R|
00000cf0  49 53 43 20 4f 53 20 74  6f 0a 63 61 6c 6c 20 61  |ISC OS to.call a|
00000d00  20 72 6f 75 74 69 6e 65  20 61 66 74 65 72 20 61  | routine after a|
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00000d30  20 63 61 6c 6c 73 20 4f  53 5f 43 61 6c 6c 45 76  | calls OS_CallEv|
00000d40  65 72 79 20 74 6f 0a 61  72 72 61 6e 67 65 20 66  |ery to.arrange f|
00000d50  6f 72 20 61 20 63 61 6c  6c 20 65 76 65 72 79 20  |or a call every |
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00000d70  74 6f 20 61 20 72 6f 75  74 69 6e 65 20 77 68 69  |to a routine whi|
00000d80  63 68 20 63 68 65 63 6b  73 20 74 68 65 20 6d 6f  |ch checks the mo|
00000d90  75 73 65 0a 70 6f 73 69  74 69 6f 6e 20 61 6e 64  |use.position and|
00000da0  20 63 61 6e 63 65 6c 73  20 74 68 65 20 64 6f 75  | cancels the dou|
00000db0  62 6c 65 2d 63 6c 69 63  6b 20 6d 6f 6e 69 74 6f  |ble-click monito|
00000dc0  72 69 6e 67 20 69 66 20  74 68 65 20 6d 6f 75 73  |ring if the mous|
00000dd0  65 20 69 73 20 6d 6f 76  65 64 20 6d 6f 72 65 0a  |e is moved more.|
00000de0  74 68 61 6e 20 61 20 63  65 72 74 61 69 6e 20 61  |than a certain a|
00000df0  6d 6f 75 6e 74 2e 0a 0a  4e 2e 42 2e 20 41 6c 74  |mount...N.B. Alt|
00000e00  68 6f 75 67 68 20 74 68  65 20 6e 6f 72 6d 61 6c  |hough the normal|
00000e10  20 64 6f 75 62 6c 65 2d  63 6c 69 63 6b 20 74 69  | double-click ti|
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00000e40  65 6d 65 6e 74 20 63 61  6e 20 62 65 20 63 6f 6e  |ement can be con|
00000e50  66 69 67 75 72 65 64 2c  20 74 68 65 72 65 20 61  |figured, there a|
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00000e70  77 61 79 20 6f 66 20 72  65 61 64 69 6e 67 20 74  |way of reading t|
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00000ea0  6c 69 61 62 6c 65 20 6d  65 74 68 6f 64 20 6f 66  |liable method of|
00000eb0  20 63 68 65 63 6b 69 6e  67 20 43 4d 4f 53 20 52  | checking CMOS R|
00000ec0  41 4d 20 6c 6f 63 61 74  69 6f 6e 73 2c 0a 77 68  |AM locations,.wh|
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00000f00  49 53 43 20 4f 53 2e 20  54 68 69 73 20 6d 6f 64  |ISC OS. This mod|
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00000f90  63 6b 73 20 66 6f 72 20  65 69 74 68 65 72 20 31  |cks for either 1|
00000fa0  30 20 68 6f 72 69 7a 6f  6e 74 61 6c 20 6f 72 0a  |0 horizontal or.|
00000fb0  31 30 20 76 65 72 74 69  63 61 6c 20 75 6e 69 74  |10 vertical unit|
00000fc0  73 20 6f 66 20 6d 6f 76  65 6d 65 6e 74 29 2e 20  |s of movement). |
00000fd0  54 68 65 73 65 20 76 61  6c 75 65 73 20 61 72 65  |These values are|
00000fe0  20 66 69 78 65 64 20 69  6e 20 74 68 69 73 20 76  | fixed in this v|
00000ff0  65 72 73 69 6f 6e 20 6f  66 0a 74 68 65 20 6d 6f  |ersion of.the mo|
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00001010  73 20 61 20 64 65 6d 61  6e 64 20 66 6f 72 20 74  |s a demand for t|
00001020  68 65 20 61 62 69 6c 69  74 79 20 74 6f 20 61 6c  |he ability to al|
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00001100  66 74 65 72 20 61 6e 64  20 63 61 6c 6c 2d 65 76  |fter and call-ev|
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00001120  64 20 61 6e 64 20 61 0a  73 65 63 6f 6e 64 20 63  |d and a.second c|
00001130  61 6c 6c 62 61 63 6b 20  69 73 20 75 73 65 64 2e  |allback is used.|
00001140  20 54 68 69 73 20 72 6f  75 74 69 6e 65 20 63 68  | This routine ch|
00001150  65 63 6b 73 20 74 68 61  74 20 74 68 65 20 73 61  |ecks that the sa|
00001160  6d 65 20 6b 65 79 20 68  61 73 20 62 65 65 6e 0a  |me key has been.|
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00001190  61 67 20 61 6e 64 20 74  61 6b 65 73 20 73 74 65  |ag and takes ste|
000011a0  70 73 20 74 6f 20 69 6e  76 65 72 74 20 74 68 65  |ps to invert the|
000011b0  20 69 63 6f 6e 2e 0a 0a  41 6c 74 68 6f 75 67 68  | icon...Although|
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000011e0  69 6e 76 65 72 74 65 64  20 62 79 20 6d 65 61 6e  |inverted by mean|
000011f0  73 20 6f 66 20 61 20 63  61 6c 6c 20 74 6f 0a 57  |s of a call to.W|
00001200  69 6d 70 5f 53 65 74 49  63 6f 6e 53 74 61 74 65  |imp_SetIconState|
00001210  2c 20 74 68 65 20 70 72  6f 63 65 64 75 72 65 20  |, the procedure |
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00001230  6c 65 2e 20 54 68 69 73  20 53 57 49 20 6d 61 79  |le. This SWI may|
00001240  20 6f 6e 6c 79 20 62 65  0a 63 61 6c 6c 65 64 20  | only be.called |
00001250  77 68 69 6c 65 20 74 68  65 20 61 70 70 6c 69 63  |while the applic|
00001260  61 74 69 6f 6e 20 77 68  69 63 68 20 6f 77 6e 73  |ation which owns|
00001270  20 74 68 65 20 69 63 6f  6e 20 69 73 20 74 68 65  | the icon is the|
00001280  20 63 75 72 72 65 6e 74  6c 79 20 61 63 74 69 76  | currently activ|
00001290  65 0a 74 61 73 6b 2e 20  49 66 20 77 65 20 73 69  |e.task. If we si|
000012a0  6d 70 6c 79 20 63 61 6c  6c 20 69 74 20 77 68 65  |mply call it whe|
000012b0  6e 20 74 68 65 20 6d 6f  75 73 65 20 69 73 20 63  |n the mouse is c|
000012c0  6c 69 63 6b 65 64 2c 20  74 68 69 73 20 6d 61 79  |licked, this may|
000012d0  20 6e 6f 74 20 62 65 20  74 68 65 0a 63 61 73 65  | not be the.case|
000012e0  2c 20 65 73 70 65 63 69  61 6c 6c 79 20 69 66 20  |, especially if |
000012f0  73 65 76 65 72 61 6c 20  6d 75 6c 74 69 2d 74 61  |several multi-ta|
00001300  73 6b 69 6e 67 20 61 70  70 6c 69 63 61 74 69 6f  |sking applicatio|
00001310  6e 73 20 61 72 65 20 72  75 6e 6e 69 6e 67 20 61  |ns are running a|
00001320  74 20 74 68 65 0a 73 61  6d 65 20 74 69 6d 65 2e  |t the.same time.|
00001330  20 57 65 20 68 61 76 65  20 74 6f 20 73 65 6e 64  | We have to send|
00001340  20 61 20 6d 65 73 73 61  67 65 20 74 6f 20 74 68  | a message to th|
00001350  65 20 74 61 73 6b 20 62  75 74 20 77 65 20 63 61  |e task but we ca|
00001360  6e 6e 6f 74 2c 20 6f 66  20 63 6f 75 72 73 65 2c  |nnot, of course,|
00001370  0a 72 65 77 72 69 74 65  20 69 74 73 20 73 6f 66  |.rewrite its sof|
00001380  74 77 61 72 65 2e 0a 0a  54 68 65 20 73 6f 6c 75  |tware...The solu|
00001390  74 69 6f 6e 20 69 73 20  74 6f 20 75 73 65 20 61  |tion is to use a|
000013a0  20 66 69 6c 74 65 72 2e  20 57 65 20 63 6f 75 6c  | filter. We coul|
000013b0  64 20 75 73 65 20 61 20  70 72 65 2d 66 69 6c 74  |d use a pre-filt|
000013c0  65 72 2c 20 77 68 69 63  68 20 69 73 20 63 61 6c  |er, which is cal|
000013d0  6c 65 64 0a 6a 75 73 74  20 62 65 66 6f 72 65 20  |led.just before |
000013e0  57 69 6d 70 5f 50 6f 6c  6c 20 69 73 20 65 78 65  |Wimp_Poll is exe|
000013f0  63 75 74 65 64 2c 20 6f  72 20 61 20 70 6f 73 74  |cuted, or a post|
00001400  2d 66 69 6c 74 65 72 20  77 68 69 63 68 20 69 73  |-filter which is|
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00001420  6e 20 66 72 6f 6d 20 57  69 6d 70 5f 50 6f 6c 6c  |n from Wimp_Poll|
00001430  2e 20 49 6e 20 74 68 69  73 20 63 61 73 65 2c 20  |. In this case, |
00001440  77 65 20 75 73 65 20 74  68 65 20 6c 61 74 74 65  |we use the latte|
00001450  72 2e 20 54 68 65 20 74  65 63 68 6e 69 71 75 65  |r. The technique|
00001460  20 69 73 20 74 6f 0a 73  65 6e 64 20 61 20 75 6e  | is to.send a un|
00001470  69 71 75 65 20 6d 65 73  73 61 67 65 20 74 6f 20  |ique message to |
00001480  74 68 65 20 74 61 73 6b  20 77 68 69 63 68 20 6f  |the task which o|
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000014a0  6e 74 65 72 63 65 70 74  20 61 6e 64 0a 72 65 63  |ntercept and.rec|
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000014c0  69 74 20 74 6f 20 69 6e  76 65 72 74 20 6f 72 20  |it to invert or |
000014d0  64 65 2d 69 6e 76 65 72  74 20 74 68 65 20 72 65  |de-invert the re|
000014e0  71 75 69 72 65 64 20 69  63 6f 6e 2e 0a 0a 57 65  |quired icon...We|
000014f0  20 63 6f 75 6c 64 20 73  65 6e 64 20 61 20 6d 65  | could send a me|
00001500  73 73 61 67 65 2c 20 75  73 69 6e 67 20 72 65 61  |ssage, using rea|
00001510  73 6f 6e 20 63 6f 64 65  20 31 37 20 6f 72 20 31  |son code 17 or 1|
00001520  38 2c 20 62 75 74 20 77  65 20 77 6f 75 6c 64 20  |8, but we would |
00001530  68 61 76 65 20 74 6f 0a  66 69 6e 64 20 61 20 6d  |have to.find a m|
00001540  65 73 73 61 67 65 20 61  63 74 69 6f 6e 20 63 6f  |essage action co|
00001550  64 65 20 74 68 61 74 20  69 73 20 6e 6f 74 20 75  |de that is not u|
00001560  73 65 64 20 66 6f 72 20  61 6e 79 74 68 69 6e 67  |sed for anything|
00001570  20 65 6c 73 65 2c 20 77  68 69 63 68 20 77 6f 75  | else, which wou|
00001580  6c 64 0a 70 72 65 73 65  6e 74 20 70 72 6f 62 6c  |ld.present probl|
00001590  65 6d 73 2e 20 49 74 20  69 73 20 61 6c 73 6f 20  |ems. It is also |
000015a0  70 65 72 6d 69 73 73 69  62 6c 65 20 66 6f 72 20  |permissible for |
000015b0  61 20 74 61 73 6b 20 74  6f 20 6d 61 73 6b 20 6f  |a task to mask o|
000015c0  75 74 20 74 68 65 73 65  20 72 65 61 73 6f 6e 0a  |ut these reason.|
000015d0  63 6f 64 65 73 2c 20 77  68 69 63 68 20 77 6f 75  |codes, which wou|
000015e0  6c 64 20 70 72 65 76 65  6e 74 20 6f 75 72 20 6d  |ld prevent our m|
000015f0  65 73 73 61 67 65 20 67  65 74 74 69 6e 67 20 74  |essage getting t|
00001600  68 72 6f 75 67 68 2e 20  53 6f 20 74 68 61 74 20  |hrough. So that |
00001610  74 68 69 73 20 63 61 6e  6e 6f 74 0a 68 61 70 70  |this cannot.happ|
00001620  65 6e 2c 20 74 68 65 20  6d 6f 64 75 6c 65 20 73  |en, the module s|
00001630  65 6e 64 73 20 61 20 6d  65 73 73 61 67 65 20 77  |ends a message w|
00001640  69 74 68 20 72 65 61 73  6f 6e 20 63 6f 64 65 20  |ith reason code |
00001650  32 2c 20 77 68 69 63 68  20 75 73 75 61 6c 6c 79  |2, which usually|
00001660  20 6d 65 61 6e 73 0a 27  6f 70 65 6e 20 77 69 6e  | means.'open win|
00001670  64 6f 77 20 72 65 71 75  65 73 74 27 2e 20 54 68  |dow request'. Th|
00001680  69 73 20 72 65 61 73 6f  6e 20 63 6f 64 65 20 69  |is reason code i|
00001690  73 20 6e 6f 74 20 73 75  70 70 6f 73 65 64 20 74  |s not supposed t|
000016a0  6f 20 62 65 20 6d 61 73  6b 65 64 20 6f 75 74 0a  |o be masked out.|
000016b0  77 68 65 6e 20 63 61 6c  6c 69 6e 67 20 57 69 6d  |when calling Wim|
000016c0  70 5f 50 6f 6c 6c 2e 20  4f 75 72 20 6d 65 73 73  |p_Poll. Our mess|
000016d0  61 67 65 20 73 65 6e 64  73 20 52 31 2b 30 20 61  |age sends R1+0 a|
000016e0  73 20 7a 65 72 6f 20 61  6e 64 20 52 31 2b 34 20  |s zero and R1+4 |
000016f0  61 73 0a 26 37 32 36 43  34 33 34 39 2c 20 77 68  |as.&726C4349, wh|
00001700  69 63 68 20 69 73 20 74  68 65 20 41 53 43 49 49  |ich is the ASCII|
00001710  20 63 6f 64 65 20 66 6f  72 20 27 49 43 6c 72 27  | code for 'IClr'|
00001720  2e 20 54 68 69 73 20 63  6f 72 72 65 73 70 6f 6e  |. This correspon|
00001730  64 73 20 74 6f 20 61 20  72 65 71 75 65 73 74 0a  |ds to a request.|
00001740  74 6f 20 6f 70 65 6e 20  74 68 65 20 77 69 6e 64  |to open the wind|
00001750  6f 77 20 77 68 6f 73 65  20 68 61 6e 64 6c 65 20  |ow whose handle |
00001760  69 73 20 7a 65 72 6f 2c  20 77 69 74 68 20 61 20  |is zero, with a |
00001770  6d 69 6e 69 6d 75 6d 20  78 20 63 6f 6f 72 64 69  |minimum x coordi|
00001780  6e 61 74 65 20 6f 66 0a  26 37 32 36 43 34 33 34  |nate of.&726C434|
00001790  39 20 2d 20 61 20 6d 6f  73 74 20 75 6e 6c 69 6b  |9 - a most unlik|
000017a0  65 6c 79 20 73 74 61 74  65 20 6f 66 20 61 66 66  |ely state of aff|
000017b0  61 69 72 73 20 69 6e 20  61 6e 79 20 6f 74 68 65  |airs in any othe|
000017c0  72 20 73 69 74 75 61 74  69 6f 6e 21 20 54 68 65  |r situation! The|
000017d0  0a 74 68 69 72 64 20 77  6f 72 64 20 69 6e 20 74  |.third word in t|
000017e0  68 65 20 62 6c 6f 63 6b  20 69 73 20 7a 65 72 6f  |he block is zero|
000017f0  20 74 6f 20 63 6c 65 61  72 20 74 68 65 20 69 63  | to clear the ic|
00001800  6f 6e 20 6f 72 20 31 20  74 6f 20 69 6e 76 65 72  |on or 1 to inver|
00001810  74 20 69 74 2e 20 54 68  65 0a 66 69 6c 74 65 72  |t it. The.filter|
00001820  20 69 73 20 73 65 74 20  74 6f 20 68 61 6e 64 6c  | is set to handl|
00001830  65 20 6f 6e 6c 79 20 72  65 61 73 6f 6e 20 63 6f  |e only reason co|
00001840  64 65 20 32 2e 20 49 66  20 69 74 20 72 65 63 65  |de 2. If it rece|
00001850  69 76 65 73 20 74 68 65  20 65 78 61 63 74 20 73  |ives the exact s|
00001860  74 61 74 65 0a 6f 66 20  61 66 66 61 69 72 73 20  |tate.of affairs |
00001870  61 73 20 64 65 73 63 72  69 62 65 64 2c 20 69 74  |as described, it|
00001880  20 65 69 74 68 65 72 20  69 6e 76 65 72 74 73 20  | either inverts |
00001890  6f 72 20 63 6c 65 61 72  73 20 74 68 65 20 69 63  |or clears the ic|
000018a0  6f 6e 20 61 6e 64 20 65  78 69 74 73 0a 77 69 74  |on and exits.wit|
000018b0  68 6f 75 74 20 70 61 73  73 69 6e 67 20 74 68 65  |hout passing the|
000018c0  20 63 61 6c 6c 20 6f 6e  74 6f 20 74 68 65 20 61  | call onto the a|
000018d0  70 70 6c 69 63 61 74 69  6f 6e 2e 0a 0a 49 66 20  |pplication...If |
000018e0  61 20 6b 65 79 20 69 73  20 70 72 65 73 73 65 64  |a key is pressed|
000018f0  20 77 68 69 6c 65 20 74  68 65 20 69 6e 76 65 72  | while the inver|
00001900  74 65 64 20 69 63 6f 6e  20 66 6c 61 67 20 69 73  |ted icon flag is|
00001910  20 73 65 74 2c 20 74 68  65 20 72 6f 75 74 69 6e  | set, the routin|
00001920  65 20 28 61 67 61 69 6e  0a 62 79 20 6d 65 61 6e  |e (again.by mean|
00001930  73 20 6f 66 20 61 20 63  61 6c 6c 62 61 63 6b 29  |s of a callback)|
00001940  20 73 65 6e 64 73 20 61  20 6d 65 73 73 61 67 65  | sends a message|
00001950  20 74 6f 20 63 6c 65 61  72 20 74 68 65 20 69 63  | to clear the ic|
00001960  6f 6e 2c 20 74 68 65 6e  20 73 65 6e 64 73 20 74  |on, then sends t|
00001970  68 65 0a 6b 65 79 70 72  65 73 73 20 63 68 61 72  |he.keypress char|
00001980  61 63 74 65 72 2c 20 70  72 65 63 65 64 65 64 20  |acter, preceded |
00001990  62 79 20 61 20 43 74 72  6c 2d 55 20 74 6f 20 64  |by a Ctrl-U to d|
000019a0  65 6c 65 74 65 20 74 68  65 20 74 65 78 74 2e 0a  |elete the text..|
000019b0  0a 54 68 65 20 6d 6f 64  75 6c 65 20 69 6e 63 6f  |.The module inco|
000019c0  72 70 6f 72 61 74 65 73  20 61 20 73 65 6c 66 2d  |rporates a self-|
000019d0  63 68 65 63 6b 69 6e 67  20 72 6f 75 74 69 6e 65  |checking routine|
000019e0  20 74 6f 20 64 65 74 65  63 74 20 63 6f 72 72 75  | to detect corru|
000019f0  70 74 69 6f 6e 20 62 79  0a 76 69 72 75 73 65 73  |ption by.viruses|
00001a00  2e 0a 0a 50 6c 65 61 73  65 20 73 65 6e 64 20 61  |...Please send a|
00001a10  6c 6c 20 63 6f 6d 6d 65  6e 74 73 20 61 6e 64 20  |ll comments and |
00001a20  73 75 67 67 65 73 74 69  6f 6e 73 20 74 6f 3a 0a  |suggestions to:.|
00001a30  0a 4d 2e 50 2e 20 46 6f  78 2c 0a 33 31 20 50 69  |.M.P. Fox,.31 Pi|
00001a40  65 72 73 6f 6e 20 52 6f  61 64 2c 0a 57 69 6e 64  |erson Road,.Wind|
00001a50  73 6f 72 2c 0a 42 65 72  6b 73 2e 20 53 4c 34 20  |sor,.Berks. SL4 |
00001a60  35 52 45                                          |5RE|
00001a63

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