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[gl] Allocate small number of rectangles on the stack

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FillRectangle is most frequently used to fill an entire imagee with the
background colour, i.e. with just a single, or few, rectangle. Avoid
heap allocation for this common case by allocating enough space for 4
rectangles (vertices+colors) on the stack.
This commit is contained in:
Chris Wilson 2009-09-03 17:47:34 +01:00
parent 6ce200da9d
commit 769f4a4f47
1 changed files with 29 additions and 14 deletions
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43
src/cairo-gl-surface.c
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@ -1522,7 +1522,10 @@ _cairo_gl_surface_fill_rectangles (void *abstract_surface,
cairo_rectangle_int_t *rects,
int num_rects)
{
#define N_STACK_RECTS 4
cairo_gl_surface_t *surface = abstract_surface;
GLfloat vertices_stack[N_STACK_RECTS*4*2];
GLfloat colors_stack[N_STACK_RECTS*4*4]
cairo_gl_context_t *ctx;
int i;
GLfloat *vertices;
@ -1536,23 +1539,32 @@ _cairo_gl_surface_fill_rectangles (void *abstract_surface,
_cairo_gl_set_destination (surface);
_cairo_gl_set_operator (surface, op);
vertices = _cairo_malloc_ab (num_rects, sizeof (GLfloat) * 4 * 2);
colors = _cairo_malloc_ab (num_rects, sizeof (GLfloat) * 4 * 4);
if (!vertices || !colors) {
_cairo_gl_context_release (ctx);
free (vertices);
free (colors);
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
if (num_rects > N_STACK_RECTS) {
vertices = _cairo_malloc_ab (num_rects, sizeof (GLfloat) * 4 * 2);
colors = _cairo_malloc_ab (num_rects, sizeof (GLfloat) * 4 * 4);
if (!vertices || !colors) {
_cairo_gl_context_release (ctx);
free (vertices);
free (colors);
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
}
} else {
vertices = vertices_stack;
colors = colors_stack;
}
/* This should be loaded in as either a blend constant and an operator
* setup specific to this, or better, a fragment shader constant.
*/
for (i = 0; i < num_rects * 4; i++) {
colors[i * 4 + 0] = color->red * color->alpha;
colors[i * 4 + 1] = color->green * color->alpha;
colors[i * 4 + 2] = color->blue * color->alpha;
colors[i * 4 + 3] = color->alpha;
colors[0] = color->red * color->alpha;
colors[1] = color->green * color->alpha;
colors[2] = color->blue * color->alpha;
colors[3] = color->alpha;
for (i = 1; i < num_rects * 4; i++) {
colors[i*4 + 0] = colors[0];
colors[i*4 + 1] = colors[1];
colors[i*4 + 2] = colors[2];
colors[i*4 + 3] = colors[3];
}
for (i = 0; i < num_rects; i++) {
@ -1570,6 +1582,7 @@ _cairo_gl_surface_fill_rectangles (void *abstract_surface,
glEnableClientState (GL_VERTEX_ARRAY);
glColorPointer (4, GL_FLOAT, sizeof (GLfloat)*4, colors);
glEnableClientState (GL_COLOR_ARRAY);
glDrawArrays (GL_QUADS, 0, 4 * num_rects);
glDisableClientState (GL_COLOR_ARRAY);
@ -1577,8 +1590,10 @@ _cairo_gl_surface_fill_rectangles (void *abstract_surface,
glDisable (GL_BLEND);
_cairo_gl_context_release (ctx);
free (vertices);
free (colors);
if (vertices != vertices_stack)
free (vertices);
if (colors != colors_stack)
free (colors);
return CAIRO_STATUS_SUCCESS;
}