add SkDeviceLooper to handle larger-than-fixedpoint

src/core/SkDraw.cpp

Index: src/core/SkDraw.cpp
diff --git a/src/core/SkDraw.cpp b/src/core/SkDraw.cpp
index 671da49d099dc826b75542944b834b4b9649851a..a9d5fbb0b63269d476a6cdba3a0263ff7d8ba28b 100644
--- a/src/core/SkDraw.cpp
+++ b/src/core/SkDraw.cpp
@@ -5,13 +5,13 @@
  * found in the LICENSE file.
  */
 
-
 #include "SkDraw.h"
 #include "SkBlitter.h"
 #include "SkBounder.h"
 #include "SkCanvas.h"
 #include "SkColorPriv.h"
 #include "SkDevice.h"
+#include "SkDeviceLooper.h"
 #include "SkFixed.h"
 #include "SkMaskFilter.h"
 #include "SkPaint.h"
@@ -873,48 +873,56 @@ void SkDraw::drawRect(const SkRect& rect, const SkPaint& paint) const {
     }
 
     // look for the quick exit, before we build a blitter
-    if (true) {
-        SkIRect ir;
-        devRect.roundOut(&ir);
-        if (paint.getStyle() != SkPaint::kFill_Style) {
-            // extra space for hairlines
-            ir.inset(-1, -1);
-        }
-        if (fRC->quickReject(ir))
-            return;
+    SkIRect ir;
+    devRect.roundOut(&ir);
+    if (paint.getStyle() != SkPaint::kFill_Style) {
+        // extra space for hairlines
+        ir.inset(-1, -1);
+    }
+    if (fRC->quickReject(ir)) {
+        return;
     }
 
-    SkAutoBlitterChoose blitterStorage(*fBitmap, matrix, paint);
-    const SkRasterClip& clip = *fRC;
-    SkBlitter*          blitter = blitterStorage.get();
-
-    // we want to "fill" if we are kFill or kStrokeAndFill, since in the latter
-    // case we are also hairline (if we've gotten to here), which devolves to
-    // effectively just kFill
-    switch (rtype) {
-        case kFill_RectType:
-            if (paint.isAntiAlias()) {
-                SkScan::AntiFillRect(devRect, clip, blitter);
-            } else {
-                SkScan::FillRect(devRect, clip, blitter);
-            }
-            break;
-        case kStroke_RectType:
-            if (paint.isAntiAlias()) {
-                SkScan::AntiFrameRect(devRect, strokeSize, clip, blitter);
-            } else {
-                SkScan::FrameRect(devRect, strokeSize, clip, blitter);
-            }
-            break;
-        case kHair_RectType:
-            if (paint.isAntiAlias()) {
-                SkScan::AntiHairRect(devRect, clip, blitter);
-            } else {
-                SkScan::HairRect(devRect, clip, blitter);
-            }
-            break;
-        default:
-            SkDEBUGFAIL("bad rtype");
+    SkDeviceLooper looper(*fBitmap, *fRC, ir, paint.isAntiAlias());
+    while (looper.next()) {

[tomhudson, 2013/08/28 10:53:05]

This injects another degree of indirection & bunch of allocations into every
drawRect() call. For large cases it's only incidental, but do we have any perf
tests that would capture impact on a page with a large number of small rectangle
draws?

[reed1, 2013/08/28 12:35:07]

There should be zero allocations in the (common) case where the rect fits inside
+- 16K. Is that not the case?

+        SkRect localDevRect;
+        looper.mapRect(&localDevRect, devRect);
+        SkMatrix localMatrix;
+        looper.mapMatrix(&localMatrix, matrix);
+
+        SkAutoBlitterChoose blitterStorage(looper.getBitmap(), localMatrix,
+                                           paint);
+        const SkRasterClip& clip = looper.getRC();
+        SkBlitter*          blitter = blitterStorage.get();
+
+        // we want to "fill" if we are kFill or kStrokeAndFill, since in the latter
+        // case we are also hairline (if we've gotten to here), which devolves to
+        // effectively just kFill
+        switch (rtype) {
+            case kFill_RectType:
+                if (paint.isAntiAlias()) {
+                    SkScan::AntiFillRect(localDevRect, clip, blitter);
+                } else {
+                    SkScan::FillRect(localDevRect, clip, blitter);
+                }
+                break;
+            case kStroke_RectType:
+                if (paint.isAntiAlias()) {
+                    SkScan::AntiFrameRect(localDevRect, strokeSize, clip, blitter);
+                } else {
+                    SkScan::FrameRect(localDevRect, strokeSize, clip, blitter);
+                }
+                break;
+            case kHair_RectType:
+                if (paint.isAntiAlias()) {
+                    SkScan::AntiHairRect(localDevRect, clip, blitter);
+                } else {
+                    SkScan::HairRect(localDevRect, clip, blitter);
+                }
+                break;
+            default:
+                SkDEBUGFAIL("bad rtype");
+        }
     }
 }
 
@@ -2825,3 +2833,4 @@ bool SkDraw::DrawToMask(const SkPath& devPath, const SkIRect* clipBounds,
 
     return true;
 }
+