/**
* Returns a pixel format identifier that is suitable for Java 2D's needs
* (must have a stencil buffer, support for pbuffers, etc). If no
* appropriate pixel format can be found, this method returns 0.
*/
static int
WGLGC_GetPixelFormatForDC(HDC hdc)
{
int attrs[] = {
WGL_PIXEL_TYPE_ARB, WGL_TYPE_RGBA_ARB,
WGL_DRAW_TO_WINDOW_ARB, GL_TRUE,
WGL_DRAW_TO_PBUFFER_ARB, GL_TRUE,
WGL_BIND_TO_TEXTURE_RGB_ARB, GL_TRUE,
WGL_DOUBLE_BUFFER_ARB, GL_TRUE,
WGL_STENCIL_BITS_ARB, 1,
0
};
int pixfmt;
int nfmts;
J2dTraceLn(J2D_TRACE_INFO, "in WGLGC_GetPixelFormatForDC");
// find pixel format
if (!j2d_wglChoosePixelFormatARB(hdc, attrs, NULL, 1, &pixfmt, &nfmts)) {
J2dTraceLn(J2D_TRACE_ERROR, "error choosing pixel format");
return 0;
}
if (nfmts <= 0) {
J2dTraceLn(J2D_TRACE_ERROR, "no pixel formats found");
return 0;
}
J2dTraceLn1(J2D_TRACE_VERBOSE, "chose pixel format: %d", pixfmt);
return pixfmt;
}
/**
* Returns a pixel format identifier that is suitable for Java 2D's needs
* (must have a depth buffer, support for pbuffers, etc). This method will
* iterate through all pixel formats (if any) that match the requested
* attributes and will attempt to find a pixel format with a minimal combined
* depth+stencil buffer. Note that we currently only need depth capabilities
* (for shape clipping purposes), but wglChoosePixelFormatARB() will often
* return a list of pixel formats with the largest depth buffer (and stencil)
* sizes at the top of the list. Therefore, we scan through the whole list
* to find the most VRAM-efficient pixel format. If no appropriate pixel
* format can be found, this method returns 0.
*/
static int
WGLGC_GetPixelFormatForDC(HDC hdc)
{
int attrs[] = {
WGL_PIXEL_TYPE_ARB, WGL_TYPE_RGBA_ARB,
WGL_DRAW_TO_WINDOW_ARB, GL_TRUE,
WGL_DRAW_TO_PBUFFER_ARB, GL_TRUE,
WGL_DOUBLE_BUFFER_ARB, GL_TRUE,
WGL_DEPTH_BITS_ARB, 16, // anything >= 16 will work for us
0
};
int pixfmts[32];
int chosenPixFmt = 0;
int nfmts, i;
// this is the initial minimum value for the combined depth+stencil size
// (we initialize it to some absurdly high value; realistic values will
// be much less than this number)
int minDepthPlusStencil = 512;
J2dRlsTraceLn(J2D_TRACE_INFO, "WGLGC_GetPixelFormatForDC");
// find all pixel formats (maximum of 32) with the provided attributes
if (!j2d_wglChoosePixelFormatARB(hdc, attrs, NULL, 32, pixfmts, &nfmts)) {
J2dRlsTraceLn(J2D_TRACE_ERROR,
"WGLGC_GetPixelFormatForDC: error choosing pixel format");
return 0;
}
if (nfmts <= 0) {
J2dRlsTraceLn(J2D_TRACE_ERROR,
"WGLGC_GetPixelFormatForDC: no pixel formats found");
return 0;
}
J2dRlsTraceLn(J2D_TRACE_VERBOSE, " candidate pixel formats:");
// iterate through the list of pixel formats, looking for the one that
// meets our requirements while keeping the combined depth+stencil sizes
// to a minimum
for (i = 0; i < nfmts; i++) {
int attrKeys[] = {
WGL_DEPTH_BITS_ARB, WGL_STENCIL_BITS_ARB,
WGL_DOUBLE_BUFFER_ARB, WGL_ALPHA_BITS_ARB
};
int attrVals[4];
int pixfmt = pixfmts[i];
int depth, stencil, db, alpha;
j2d_wglGetPixelFormatAttribivARB(hdc, pixfmt, 0, 4,
attrKeys, attrVals);
depth = attrVals[0];
stencil = attrVals[1];
db = attrVals[2];
alpha = attrVals[3];
J2dRlsTrace5(J2D_TRACE_VERBOSE,
"[V] pixfmt=%d db=%d alpha=%d depth=%d stencil=%d valid=",
pixfmt, db, alpha, depth, stencil);
if ((depth + stencil) < minDepthPlusStencil) {
J2dRlsTrace(J2D_TRACE_VERBOSE, "true\n");
minDepthPlusStencil = depth + stencil;
chosenPixFmt = pixfmt;
} else {
J2dRlsTrace(J2D_TRACE_VERBOSE, "false (large depth)\n");
}
}
if (chosenPixFmt == 0) {
J2dRlsTraceLn(J2D_TRACE_ERROR,
"WGLGC_GetPixelFormatForDC: could not find appropriate pixfmt");
return 0;
}
J2dRlsTraceLn1(J2D_TRACE_INFO,
"WGLGC_GetPixelFormatForDC: chose %d as the best pixel format",
chosenPixFmt);
return chosenPixFmt;
}