Add Sample slide for Rectanizers
R=jvanverth@google.com, bsalomon@google.com
Author: robertphillips@google.com
Review URL: https://codereview.chromium.org/303263005
diff --git a/src/gpu/GrRectanizer_pow2.h b/src/gpu/GrRectanizer_pow2.h
index c2e4565..e9d9d02 100644
--- a/src/gpu/GrRectanizer_pow2.h
+++ b/src/gpu/GrRectanizer_pow2.h
@@ -10,6 +10,11 @@
#include "GrRectanizer.h"
+// This Rectanizer quantizes the incoming rects to powers of 2. Each power
+// of two can have, at most, one active row/shelf. Once a row/shelf for
+// a particular power of two gets full its fRows entry is recycled to point
+// to a new row.
+// The skyline algorithm almost always provides a better packing.
class GrRectanizerPow2 : public GrRectanizer {
public:
GrRectanizerPow2(int w, int h) : INHERITED(w, h) {
@@ -32,9 +37,12 @@
private:
static const int kMIN_HEIGHT_POW2 = 2;
+ static const int kMaxExponent = 16;
struct Row {
GrIPoint16 fLoc;
+ // fRowHeight is actually known by this struct's position in fRows
+ // but it is used to signal if there exists an open row of this height
int fRowHeight;
bool canAddWidth(int width, int containerWidth) const {
@@ -42,14 +50,16 @@
}
};
- Row fRows[16];
+ Row fRows[kMaxExponent]; // 0-th entry will be unused
int fNextStripY;
int32_t fAreaSoFar;
static int HeightToRowIndex(int height) {
SkASSERT(height >= kMIN_HEIGHT_POW2);
- return 32 - SkCLZ(height - 1);
+ int index = 32 - SkCLZ(height - 1);
+ SkASSERT(index < kMaxExponent);
+ return index;
}
bool canAddStrip(int height) const {