Simplest way for graphics prototyping with FreshLib

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JohnFound

Joined: 16 Jun 2003
Posts: 3499
Location: Bulgaria

JohnFound 09 Dec 2016, 10:44

It was easy in the DOS days. The video memory was accessible from the user programs. Graphics programming in assembly was easy and fun.

That is why even now, the most examples for the beginners are written for DOS.

The modern OSes provide too complex API for graphics that is pretty hard for the beginners to learn.

FreshLib provides very simple way to make graphics, very close to the old DOS approach. One big array of pixels and your assembly program that to fill them up.

Here is a very simple example that illustrates how simple is to make graphics routines in FreshLib. The same code compiles for Linux and Windows:

Code:

include "%lib%/freshlib.inc"

@BinaryType GUI, compact

include "%lib%/freshlib.asm"


frmMainForm:
        ObjTemplate  tfEnd, TForm, frmMain, \
                     x = 100,        \
                     y = 50,         \
                     width = 320,    \
                     height = 240,   \
                     Visible = TRUE, \
                     OnPaint = OnFormPaint,     \
                     Caption = 'Easy drawing with FreshLib'


start:
        InitializeAll

        create  [pApplication], TApplication
        stdcall GUI.Init
        stdcall CreateFromTemplate, frmMainForm, 0
        set     [pApplication], TApplication:MainWindow, frmMain

        stdcall Run

        FinalizeAll
        stdcall TerminateAll, 0



Colors dd $ff584435, $ffBD9D86

proc OnFormPaint, .self, .canvas
begin

        mov     esi, [.canvas]
        mov     edi, [esi+TImage.pPixels]

        xor     edx, edx  ; Y coordinate

.loop_y:

        xor     ecx, ecx  ; X coordinate

.loop_x:

        mov     eax, ecx
        xor     eax, edx
        shr     eax, 5    ; 2^5 = 32px one field size.
        and     eax, 1    ; dark or light?

        mov     eax, [Colors+4*eax]

        stosd

        inc     ecx
        cmp     ecx, [esi+TImage.width]
        jl      .loop_x

        inc     edx
        cmp     edx, [esi+TImage.height]
        jl      .loop_y

        return
endp

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Last edited by JohnFound on 09 Dec 2016, 12:18; edited 1 time in total

09 Dec 2016, 10:44

avcaballero

Joined: 02 Feb 2004
Posts: 212
Location: Madrid - Spain

avcaballero 09 Dec 2016, 11:09

Interesting. What is .canvas and TImage? I guess that you paint on the HDC of the client area.

09 Dec 2016, 11:09

JohnFound

Joined: 16 Jun 2003
Posts: 3499
Location: Bulgaria

JohnFound 09 Dec 2016, 11:33

.canvas is an argument of the OnPaint event handler, that contains pointer to the canvas TImage of the window that have to be drawn.

TImage is in memory bitmap, defined following way:

Code:

struct TImage
  .width   dd ?  ; width in pixels.
  .height  dd ?  ; height in pixels.
  .pPixels dd ?  ; pointer to the pixel memory.

; follows os dependent data
ends

For the user only the first 3 fields are useful, because the following are OS dependent fields. For example for Linux TImage is defined this way: Source code

The .pPixels member of TImage contains pointer to the pixels array. Every pixel is always 32bit ARBG value, using premultiplied alpha.

09 Dec 2016, 11:33

JohnFound

Joined: 16 Jun 2003
Posts: 3499
Location: Bulgaria

JohnFound 09 Dec 2016, 12:18

I have added the missed attachment from the first post.

09 Dec 2016, 12:18

JohnFound

Joined: 16 Jun 2003
Posts: 3499
Location: Bulgaria

JohnFound 20 Dec 2016, 07:54

This example, with some additional comments has been added to the Fresh IDE examples/ directory in v2.5.1

20 Dec 2016, 07:54

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