Reduce glGets for stencil bits.

Clean up GL vs Gr rect conventions for viewport and scissor.

Review URL: http://codereview.appspot.com/4185056/

git-svn-id: http://skia.googlecode.com/svn/trunk@813 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 64 insertions, 0 deletions

diff --git a/gpu/src/GrGLIRect.h b/gpu/src/GrGLIRect.h
new file mode 100644
index 0000000000..b8638c0af9
--- /dev/null
+++ b/gpu/src/GrGLIRect.h
@@ -0,0 +1,64 @@
+#include "GrGLConfig.h"
+
+#ifndef GrGLIRect_DEFINED
+#define GrGLIRect_DEFINED
+
+/**
+ * Helper struct for dealing with the fact that Ganesh and GL use different
+ * window coordinate systems (top-down vs bottom-up)
+ */
+struct GrGLIRect {
+    GLint   fLeft;
+    GLint   fBottom;
+    GLsizei fWidth;
+    GLsizei fHeight;
+
+    void pushToGLViewport() const {
+        GR_GL(Viewport(fLeft, fBottom, fWidth, fHeight)); 
+    }
+
+    void pushToGLScissor() const {
+        GR_GL(Scissor(fLeft, fBottom, fWidth, fHeight));
+    }
+
+    void setFromGLViewport() {
+        GR_STATIC_ASSERT(sizeof(*this) == 4*sizeof(GLint));
+        GR_GL_GetIntegerv(GL_VIEWPORT, (GLint*) this);
+    }
+
+    // sometimes we have a GrIRect from the client that we
+    // want to simultaneously make relative to GL's viewport
+    // and convert from top-down to bottom-up.
+    void setRelativeTo(const GrGLIRect& glRect,
+                       int leftOffset,
+                       int topOffset,
+                       int width,
+                       int height) {
+        fLeft = glRect.fLeft + leftOffset;
+        fWidth = width;
+        fBottom = glRect.fBottom + (glRect.fHeight - topOffset - height);
+        fHeight = height;
+
+        GrAssert(fLeft >= 0);
+        GrAssert(fWidth >= 0);
+        GrAssert(fBottom >= 0);
+        GrAssert(fHeight >= 0);
+    }
+
+    bool contains(const GrGLIRect& glRect) const {
+        return fLeft <= glRect.fLeft &&
+               fBottom <= glRect.fBottom &&
+               fLeft + fWidth >=  glRect.fLeft + glRect.fWidth &&
+               fBottom + fHeight >=  glRect.fBottom + glRect.fHeight;
+    }
+
+    void invalidate() {fLeft = fWidth = fBottom = fHeight = -1;}
+
+    bool operator ==(const GrGLIRect& glRect) const {
+        return 0 == memcmp(this, &glRect, sizeof(GrGLIRect));
+    }
+
+    bool operator !=(const GrGLIRect& glRect) const {return !(*this == glRect);}
+};
+
+#endif
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