[fpc-pascal] AggPas / PTCGraph dynamic memory allocation
james at productionautomation.net
Sat Nov 11 02:48:43 CET 2017
I've been trying to figure out how to dynamically allocate memory to be used as a screen buffer to display AggPas generated images with PTCGraph. I don't want it hard coded because I do not know what resolution monitor is going to be used. Here is where I am at:
I can define a static variable like this:
RGB_Width = 2;
data: array[0.. (Buffer_Width+1) * (Buffer_Height+1)] of word; // I don't know why I need the +1's but it won't work without them
Then I attach it to AggPas with:
agg^.attach(@graph_buffer.data, graph_buffer.width, graph_buffer.height, - graph_buffer.width * RGB_Width);
Then I put it on the screen with:
I should point out that I like to do this:
Original_screen:=graph_buffer; to save my screen then put new stuff on it, then just copy back the original and putimage it back when I'm done. So I need a solution that will allow me to do this. I also don't always use the whole screen, sometimes I just want to getimage a little area, and putimage that back... but I don't know the size of these areas... they are calculated based on the resolution of the monitor and various settings and configurations.
Here is where I am at with my attempt to make the memory dynamically allocated:
I can use a dynamic method with PTCGraph with getimage and putimage
But if I allocate memory this way, while it works fine with getimage and putimage, I can't figure out how to use it with AggPas because the first 3 words are not part of the bitmap data... It seems like there should be a way to make this work but the solution eludes me.
I've been trying to come up with a way to do *something* like this:
Max_X, Max_Y: Word;
Max_X:=1920; //these will be detected by PTCGraph...
Size := ImageSize(0, 0, Max_X-1, Max_Y-1);
GetImage(0, 0, Max_X-1, Max_Y-1, graph_buffer^);
agg^.attach(@graph_buffer, Max_X-1,Max_Y-1, -(Max_X-1) * RGB_Width); //graph_buffer is to skip over the 3 longints 4 bytes each
The problem is with Agg^.attac() of course now graph_buffer isn't an array anymore... so what I have won't work and I haven' figured out how to attach AggPas at a position where the bitmap data is so I can use PutImage and still have the Longints that were put in by GetImage.
Any advice is greatly appreciated
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