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Topic: Resizing a Graphicbox (Read 611 times) |
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Richard Russell
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Posts: 1348
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Resizing a Graphicbox
« Thread started on: Sep 16th, 2016, 7:21pm » |
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A question has been asked over at the LB Community Forum about resizing a graphicbox. My immediate reaction was "what's the problem?" because surely you can simply use the LOCATE command to change the position and size of a graphicbox, just like any other control. The code below works in LBB but for some reason it doesn't work in LB 4 - the bitmap never seems to show. Am I doing something wrong, or is there an incompatibility that I'm not aware of?
Richard.
Code: nomainwin
WindowWidth = 800
WindowHeight = 600
graphicbox #w.gb, 0, 0, 0, 0
open "Graphicbox resize" for window as #w
do
filedialog "Select a BMP file", "*.bmp", bmpfile$
#w.gb "cls; down; fill buttonface"
#w "refresh"
if bmpfile$ = "" then close #w : end
loadbmp "bitmap", bmpfile$
hbitmap = hbmp("bitmap")
struct bitmap, bmType as long, bmWidth as long, bmHeight as long, _
bmWidthBytes as long, bmPlanes as word, _
bmBitsPixel as word, bmBits as ptr
size = len(bitmap.struct)
calldll #gdi32, "GetObjectA", hbitmap as ulong, size as long, _
bitmap as struct, ret as long
width = bitmap.bmWidth.struct
height = bitmap.bmHeight.struct
xpos = int((WindowWidth - width) / 2)
ypos = int((WindowHeight - height) / 2)
#w.gb "locate ";xpos;" ";ypos;" ";width;" ";height
#w.gb "drawbmp bitmap 0 0"
#w "refresh"
loop until 0
wait |
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Rod
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Re: Resizing a Graphicbox
« Reply #1 on: Sep 16th, 2016, 8:32pm » |
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Think it is the FLUSH command that is less necessary in LBB.
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Richard Russell
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Re: Resizing a Graphicbox
« Reply #2 on: Sep 16th, 2016, 9:28pm » |
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on Sep 16th, 2016, 8:32pm, Rod wrote:| Think it is the FLUSH command that is less necessary in LBB. |
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You're right, but it also seems that the order in which you do things is important: if I put the refresh immediately after the locate like this it still doesn't work in LB 4 even with a flush:
Code: #w.gb "locate ";xpos;" ";ypos;" ";width;" ";height
#w "refresh"
#w.gb "drawbmp bitmap 0 0"
#w.gb "flush"
But if I move the refresh to after the drawbmp it starts working:
Code: #w.gb "locate ";xpos;" ";ypos;" ";width;" ";height
#w.gb "drawbmp bitmap 0 0"
#w "refresh"
#w.gb "flush"
This isn't what I would expect, and anyway flush is usually only necessary to make graphics 'stick' rather than to cause them to display initially.
Maybe you could tell the OP that, with care, he can resize the graphicbox.
Richard.
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Rod
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Posts: 110
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Re: Resizing a Graphicbox
« Reply #3 on: Sep 17th, 2016, 4:08pm » |
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I vaguely recall this issue coming up before. It seems as if the refresh command in LB is like issuing an event. But LB needs to handle the event so needs a scan or wait or some other drawing action to recognise the refresh event has been asked for. Scan catches it, but its probably not a useful solution. A LB bug I think.
Code:nomainwin
WindowWidth = 800
WindowHeight = 600
graphicbox #w.gb, 0, 0, 0, 0
open "Graphicbox resize" for window as #w
do
filedialog "Select a BMP file", "*.bmp", bmpfile$
#w.gb "cls; down; fill buttonface"
#w "refresh"
if bmpfile$ = "" then close #w : end
loadbmp "bitmap", bmpfile$
hbitmap = hbmp("bitmap")
struct bitmap, bmType as long, bmWidth as long, bmHeight as long, _
bmWidthBytes as long, bmPlanes as word, _
bmBitsPixel as word, bmBits as ptr
size = len(bitmap.struct)
calldll #gdi32, "GetObjectA", hbitmap as ulong, size as long, _
bitmap as struct, ret as long
width = bitmap.bmWidth.struct
height = bitmap.bmHeight.struct
xpos = int((WindowWidth - width) / 2)
ypos = int((WindowHeight - height) / 2)
#w.gb "locate ";xpos;" ";ypos;" ";width;" ";height
#w "refresh"
scan
#w.gb "drawbmp bitmap 0 0; flush"
loop until 0
wait
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Richard Russell
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Posts: 1348
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Re: Resizing a Graphicbox
« Reply #4 on: Sep 17th, 2016, 5:24pm » |
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on Sep 17th, 2016, 4:08pm, Rod wrote:| It seems as if the refresh command in LB is like issuing an event. But LB needs to handle the event so needs a scan or wait or some other drawing action to recognise the refresh event has been asked for. Scan catches it, but its probably not a useful solution. |
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Interesting. This is an aspect of LB that I wasn't previously aware of. I can often guess what's going on behind the scenes to explain its behaviour, but I can't this time. 
Richard.
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