gl: Introduce a temporary texture unit

...and use it for image uploads. This makes sure that the texture units
used for SOURCE and MASK get not clobbered when images get uploaded to
textures.

4 files changed, 28 insertions, 1 deletions

diff --git a/src/cairo-gl-composite.c b/src/cairo-gl-composite.c
index f7206140..1b7f6bb3 100644
--- a/src/cairo-gl-composite.c
+++ b/src/cairo-gl-composite.c
@@ -181,6 +181,7 @@ _cairo_gl_create_gradient_texture (cairo_gl_surface_t *dst,
     glUnmapBufferARB (GL_PIXEL_UNPACK_BUFFER_ARB);
 
     glGenTextures (1, tex);
+    _cairo_gl_context_activate (ctx, CAIRO_GL_TEX_TEMP);
     glBindTexture (GL_TEXTURE_1D, *tex);
     glTexImage1D (GL_TEXTURE_1D, 0, GL_RGBA8, tex_width, 0,
                   GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, 0);
@@ -642,6 +643,7 @@ _cairo_gl_operand_setup_fixed (cairo_gl_operand_t *operand,
     }
 
     switch (tex_unit) {
+    case CAIRO_GL_TEX_TEMP:
     default:
         ASSERT_NOT_REACHED;
         break;
diff --git a/src/cairo-gl-device.c b/src/cairo-gl-device.c
index 2e6bfb94..af897f15 100644
--- a/src/cairo-gl-device.c
+++ b/src/cairo-gl-device.c
@@ -214,6 +214,8 @@ _cairo_gl_context_init (cairo_gl_context_t *ctx)
     glGetIntegerv (GL_MAX_RENDERBUFFER_SIZE, &ctx->max_framebuffer_size);
     ctx->max_texture_size = 0;
     glGetIntegerv (GL_MAX_TEXTURE_SIZE, &ctx->max_texture_size);
+    ctx->max_textures = 0;
+    glGetIntegerv (GL_MAX_TEXTURE_UNITS, &ctx->max_textures);
 
     for (n = 0; n < ARRAY_LENGTH (ctx->glyph_cache); n++)
 	_cairo_gl_glyph_cache_init (&ctx->glyph_cache[n]);
@@ -221,6 +223,21 @@ _cairo_gl_context_init (cairo_gl_context_t *ctx)
     return CAIRO_STATUS_SUCCESS;
 }
 
+void
+_cairo_gl_context_activate (cairo_gl_context_t *ctx,
+                            cairo_gl_tex_t      tex_unit)
+{
+    if (ctx->max_textures <= (GLint) tex_unit) {
+        if (tex_unit < 2) {
+            _cairo_gl_composite_flush (ctx);
+            _cairo_gl_context_destroy_operand (ctx, ctx->max_textures - 1);   
+        }
+        glActiveTexture (ctx->max_textures - 1);
+    } else {
+        glActiveTexture (GL_TEXTURE0 + tex_unit);
+    }
+}
+
 static void
 _cairo_gl_ensure_framebuffer (cairo_gl_context_t *ctx,
                               cairo_gl_surface_t *surface)
diff --git a/src/cairo-gl-private.h b/src/cairo-gl-private.h
index eaf11434..a6aea40b 100644
--- a/src/cairo-gl-private.h
+++ b/src/cairo-gl-private.h
@@ -90,7 +90,8 @@ typedef struct cairo_gl_glyph_cache {
 
 typedef enum cairo_gl_tex {
     CAIRO_GL_TEX_SOURCE = 0,
-    CAIRO_GL_TEX_MASK = 1
+    CAIRO_GL_TEX_MASK = 1,
+    CAIRO_GL_TEX_TEMP = 2
 } cairo_gl_tex_t;
 
 typedef enum cairo_gl_operand_type {
@@ -167,6 +168,7 @@ typedef struct _cairo_gl_context {
     GLuint vbo;
     GLint max_framebuffer_size;
     GLint max_texture_size;
+    GLint max_textures;
     GLenum tex_target;
 
     const cairo_gl_shader_impl_t *shader_impl;
@@ -279,6 +281,10 @@ _cairo_gl_context_acquire (cairo_device_t *device,
 cairo_private void
 _cairo_gl_context_set_destination (cairo_gl_context_t *ctx, cairo_gl_surface_t *surface);
 
+cairo_private void
+_cairo_gl_context_activate (cairo_gl_context_t *ctx,
+                            cairo_gl_tex_t      tex_unit);
+
 cairo_private cairo_bool_t
 _cairo_gl_operator_is_supported (cairo_operator_t op);
 
diff --git a/src/cairo-gl-surface.c b/src/cairo-gl-surface.c
index 9a75e28d..59053a43 100644
--- a/src/cairo-gl-surface.c
+++ b/src/cairo-gl-surface.c
@@ -281,6 +281,7 @@ _cairo_gl_surface_create_scratch (cairo_gl_context_t   *ctx,
     }
 
     /* Create the texture used to store the surface's data. */
+    _cairo_gl_context_activate (ctx, CAIRO_GL_TEX_TEMP);
     glGenTextures (1, &surface->tex);
     glBindTexture (ctx->tex_target, surface->tex);
     glTexParameteri (ctx->tex_target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
@@ -525,6 +526,7 @@ _cairo_gl_surface_draw_image (cairo_gl_surface_t *dst,
     glPixelStorei (GL_UNPACK_ALIGNMENT, 1);
     glPixelStorei (GL_UNPACK_ROW_LENGTH, src->stride / cpp);
     if (_cairo_gl_surface_is_texture (dst)) {
+        _cairo_gl_context_activate (ctx, CAIRO_GL_TEX_TEMP);
 	glBindTexture (ctx->tex_target, dst->tex);
 	glTexParameteri (ctx->tex_target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 	glTexParameteri (ctx->tex_target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);