Add support for Cairo on GL

1 files changed, 102 insertions, 0 deletions

diff --git a/pugl/cairo_gl.h b/pugl/cairo_gl.h
new file mode 100644
index 0000000..a558b42
--- /dev/null
+++ b/pugl/cairo_gl.h
@@ -0,0 +1,102 @@
+/*
+  Copyright 2016 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#if defined(PUGL_HAVE_GL) && defined(PUGL_HAVE_CAIRO)
+
+#include <stdint.h>
+
+typedef struct {
+	unsigned texture_id;
+	uint8_t* buffer;
+} PuglCairoGL;
+
+static cairo_surface_t*
+pugl_cairo_gl_create(PuglCairoGL* ctx, int width, int height, int bpp)
+{
+	free(ctx->buffer);
+	ctx->buffer = (uint8_t*)calloc(bpp * width * height, sizeof(uint8_t));
+	if (!ctx->buffer) {
+		fprintf(stderr, "failed to allocate surface buffer\n");
+		return NULL;
+	}
+
+	return cairo_image_surface_create_for_data(
+		ctx->buffer, CAIRO_FORMAT_ARGB32, width, height, bpp * width);
+}
+
+static void
+pugl_cairo_gl_free(PuglCairoGL* ctx)
+{
+	free(ctx->buffer);
+	ctx->buffer = NULL;
+}
+
+static void
+pugl_cairo_gl_configure(PuglCairoGL* ctx, int width, int height)
+{
+	glDisable(GL_DEPTH_TEST);
+	glEnable(GL_BLEND);
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+	glEnable(GL_TEXTURE_RECTANGLE_ARB);
+
+	glMatrixMode(GL_PROJECTION);
+	glLoadIdentity();
+	glOrtho(-1.0f, 1.0f, -1.0f, 1.0f, -1.0f, 1.0f);
+
+	glClear(GL_COLOR_BUFFER_BIT);
+
+	glDeleteTextures(1, &ctx->texture_id);
+	glGenTextures(1, &ctx->texture_id);
+	glBindTexture(GL_TEXTURE_RECTANGLE_ARB, ctx->texture_id);
+	glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
+}
+
+static void
+pugl_cairo_gl_draw(PuglCairoGL* ctx, int width, int height)
+{
+	glMatrixMode(GL_MODELVIEW);
+	glLoadIdentity();
+	glViewport(0, 0, width, height);
+	glClear(GL_COLOR_BUFFER_BIT);
+
+	glPushMatrix();
+	glEnable(GL_TEXTURE_RECTANGLE_ARB);
+	glEnable(GL_TEXTURE_2D);
+
+	glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA8,
+	             width, height, 0,
+	             GL_BGRA, GL_UNSIGNED_BYTE, ctx->buffer);
+
+	glBegin(GL_QUADS);
+	glTexCoord2f(0.0f, (GLfloat)height);
+	glVertex2f(-1.0f, -1.0f);
+
+	glTexCoord2f((GLfloat)width, (GLfloat)height);
+	glVertex2f(1.0f, -1.0f);
+
+	glTexCoord2f((GLfloat)width, 0.0f);
+	glVertex2f(1.0f, 1.0f);
+
+	glTexCoord2f(0.0f, 0.0f);
+	glVertex2f(-1.0f, 1.0f);
+	glEnd();
+
+	glDisable(GL_TEXTURE_2D);
+	glDisable(GL_TEXTURE_RECTANGLE_ARB);
+	glPopMatrix();
+}
+
+#endif