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//
// "$Id$"
//
// Rectangle drawing routines for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2016 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file. If this
// file is missing or damaged, see the license at:
//
// http://www.fltk.org/COPYING.php
//
// Please report all bugs and problems on the following page:
//
// http://www.fltk.org/str.php
//
#include <config.h>
#include "../../config_lib.h"
#include "Fl_GDI_Graphics_Driver.h"
const char *Fl_GDI_Graphics_Driver::class_id = "Fl_GDI_Graphics_Driver";
// FIXME: move to printer graphics driver
const char *Fl_GDI_Printer_Graphics_Driver::class_id = "Fl_GDI_Printer_Graphics_Driver";
/*
* By linking this module, the following static method will instatiate the
* MSWindows GDI Graphics driver as the main display driver.
*/
Fl_Graphics_Driver *Fl_Graphics_Driver::newMainGraphicsDriver()
{
return new Fl_GDI_Graphics_Driver();
}
// Code used to switch output to an off-screen window. See macros in
// win32.H which save the old state in local variables.
typedef struct { BYTE a; BYTE b; BYTE c; BYTE d; } FL_BLENDFUNCTION;
typedef BOOL (WINAPI* fl_alpha_blend_func)
(HDC,int,int,int,int,HDC,int,int,int,int,FL_BLENDFUNCTION);
static fl_alpha_blend_func fl_alpha_blend = NULL;
static FL_BLENDFUNCTION blendfunc = { 0, 0, 255, 1};
/*
* This function checks if the version of MSWindows that we
* curently run on supports alpha blending for bitmap transfers
* and finds the required function if so.
*/
char Fl_GDI_Graphics_Driver::can_do_alpha_blending() {
static char been_here = 0;
static char can_do = 0;
// do this test only once
if (been_here) return can_do;
been_here = 1;
// load the library that implements alpha blending
HMODULE hMod = LoadLibrary("MSIMG32.DLL");
// give up if that doesn't exist (Win95?)
if (!hMod) return 0;
// now find the blending function inside that dll
fl_alpha_blend = (fl_alpha_blend_func)GetProcAddress(hMod, "AlphaBlend");
// give up if we can't find it (Win95)
if (!fl_alpha_blend) return 0;
// we have the call, but does our display support alpha blending?
// get the desktop's device context
HDC dc = GetDC(0L);
if (!dc) return 0;
// check the device capabilities flags. However GetDeviceCaps
// does not return anything useful, so we have to do it manually:
HBITMAP bm = CreateCompatibleBitmap(dc, 1, 1);
HDC new_gc = CreateCompatibleDC(dc);
int save = SaveDC(new_gc);
SelectObject(new_gc, bm);
/*COLORREF set = */ SetPixel(new_gc, 0, 0, 0x01010101);
BOOL alpha_ok = fl_alpha_blend(dc, 0, 0, 1, 1, new_gc, 0, 0, 1, 1, blendfunc);
RestoreDC(new_gc, save);
DeleteDC(new_gc);
DeleteObject(bm);
ReleaseDC(0L, dc);
if (alpha_ok) can_do = 1;
return can_do;
}
HDC fl_makeDC(HBITMAP bitmap) {
HDC new_gc = CreateCompatibleDC(fl_gc);
SetTextAlign(new_gc, TA_BASELINE|TA_LEFT);
SetBkMode(new_gc, TRANSPARENT);
#if USE_COLORMAP
if (fl_palette) SelectPalette(new_gc, fl_palette, FALSE);
#endif
SelectObject(new_gc, bitmap);
return new_gc;
}
void Fl_GDI_Graphics_Driver::copy_offscreen(int x,int y,int w,int h,HBITMAP bitmap,int srcx,int srcy) {
HDC new_gc = CreateCompatibleDC(fl_gc);
int save = SaveDC(new_gc);
SelectObject(new_gc, bitmap);
BitBlt(fl_gc, x, y, w, h, new_gc, srcx, srcy, SRCCOPY);
RestoreDC(new_gc, save);
DeleteDC(new_gc);
}
void Fl_GDI_Graphics_Driver::copy_offscreen_with_alpha(int x,int y,int w,int h,HBITMAP bitmap,int srcx,int srcy) {
HDC new_gc = CreateCompatibleDC(fl_gc);
int save = SaveDC(new_gc);
SelectObject(new_gc, bitmap);
BOOL alpha_ok = 0;
// first try to alpha blend
if ( can_do_alpha_blending() ) {
alpha_ok = fl_alpha_blend(fl_gc, x, y, w, h, new_gc, srcx, srcy, w, h, blendfunc);
}
// if that failed (it shouldn't), still copy the bitmap over, but now alpha is 1
if (!alpha_ok) {
BitBlt(fl_gc, x, y, w, h, new_gc, srcx, srcy, SRCCOPY);
}
RestoreDC(new_gc, save);
DeleteDC(new_gc);
}
//
// End of "$Id$".
//
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