Add ability to ninepatch blurred rounded rectangle

src/effects/SkBlurMaskFilter.cpp

Index: src/effects/SkBlurMaskFilter.cpp
diff --git a/src/effects/SkBlurMaskFilter.cpp b/src/effects/SkBlurMaskFilter.cpp
index 6a5a39778cb73a6b1bdeeaf62a221437da389c34..df754d23bc0a0c3fe556379a131e5ef8d8abd2e7 100644
--- a/src/effects/SkBlurMaskFilter.cpp
+++ b/src/effects/SkBlurMaskFilter.cpp
@@ -11,6 +11,7 @@
 #include "SkGpuBlurUtils.h"
 #include "SkFlattenableBuffers.h"
 #include "SkMaskFilter.h"
+#include "SkRRect.h"
 #include "SkRTConf.h"
 #include "SkStringUtils.h"
 #include "SkStrokeRec.h"
@@ -52,6 +53,10 @@ protected:
                                            const SkIRect& clipBounds,
                                            NinePatch*) const SK_OVERRIDE;
 
+    virtual FilterReturn filterRRectToNine(const SkRRect&, const SkMatrix&,
+                                           const SkIRect& clipBounds,
+                                           NinePatch*) const SK_OVERRIDE;
+
     bool filterRectMask(SkMask* dstM, const SkRect& r, const SkMatrix& matrix,
                         SkIPoint* margin, SkMask::CreateMode createMode) const;
 
@@ -155,29 +160,44 @@ bool SkBlurMaskFilterImpl::filterRectMask(SkMask* dst, const SkRect& r,
 
 #include "SkCanvas.h"
 
-static bool drawRectsIntoMask(const SkRect rects[], int count, SkMask* mask) {
-    rects[0].roundOut(&mask->fBounds);
-    mask->fRowBytes = SkAlign4(mask->fBounds.width());
-    mask->fFormat = SkMask::kA8_Format;
-    size_t size = mask->computeImageSize();
-    mask->fImage = SkMask::AllocImage(size);
-    if (NULL == mask->fImage) {
-        return false;
-    }
-    sk_bzero(mask->fImage, size);
-
-    SkBitmap bitmap;
-    bitmap.setConfig(SkBitmap::kA8_Config,
-                     mask->fBounds.width(), mask->fBounds.height(),
-                     mask->fRowBytes);
-    bitmap.setPixels(mask->fImage);
-
-    SkCanvas canvas(bitmap);
-    canvas.translate(-SkIntToScalar(mask->fBounds.left()),
-                     -SkIntToScalar(mask->fBounds.top()));
+// Common code used by both draw_rrect_into_mask and drawRectsIntoMask.

[reed1, 2013/11/04 17:46:52]

errrrrrr, a giant macro with an embedded return? Did a conventional helper
function not work?

e.g.

static bool prepare_mask(const SkRect& bounds, SkMask* mask) {
    ...
}

[scroggo, 2013/11/04 19:52:54]

Ideally, I'd like to share common code for creating the SkCanvas (and
translating it to the right position). Since SkCanvas does not provide a way to
change its device, I originally allocated a new SkCanvas, which allows that, at
the cost of the extra allocation. The latest patch just accepts some code
duplication.

+// After this macro, mask has been set to bounds, its fImage has been
+// allocated, and there is a new SkCanvas (called 'canvas') with its
+// translation set to draw into, and a new SkPaint with antialias exists
+// for drawing into it.
+#define PREPARE_TO_DRAW_INTO_MASK(bounds, mask)                     \
+    SkASSERT(mask != NULL);                                         \
+                                                                    \
+    bounds.roundOut(&mask->fBounds);                                \
+    mask->fRowBytes = SkAlign4(mask->fBounds.width());              \
+    mask->fFormat = SkMask::kA8_Format;                             \
+    const size_t size = mask->computeImageSize();                   \
+    mask->fImage = SkMask::AllocImage(size);                        \
+    if (NULL == mask->fImage) {                                     \
+        return false;                                               \
+    }                                                               \
+                                                                    \
+    sk_bzero(mask->fImage, size);                                   \
+    SkBitmap bitmap;                                                \
+    bitmap.setConfig(SkBitmap::kA8_Config,                          \
+                     mask->fBounds.width(), mask->fBounds.height(), \
+                     mask->fRowBytes);                              \
+    bitmap.setPixels(mask->fImage);                                 \
+                                                                    \
+    SkCanvas canvas(bitmap);                                        \
+    canvas.translate(-SkIntToScalar(mask->fBounds.left()),          \
+                     -SkIntToScalar(mask->fBounds.top()));          \
+    SkPaint paint;                                                  \
+    paint.setAntiAlias(true)
+
+static bool draw_rrect_into_mask(const SkRRect rrect, SkMask* mask) {
+    PREPARE_TO_DRAW_INTO_MASK(rrect.rect(), mask);
+    canvas.drawRRect(rrect, paint);
+    return true;
+}
 
-    SkPaint paint;
-    paint.setAntiAlias(true);
+static bool drawRectsIntoMask(const SkRect rects[], int count, SkMask* mask) {
+    PREPARE_TO_DRAW_INTO_MASK(rects[0], mask);
 
     if (1 == count) {
         canvas.drawRect(rects[0], paint);
@@ -197,6 +217,109 @@ static bool rect_exceeds(const SkRect& r, SkScalar v) {
            r.width() > v || r.height() > v;
 }
 
+SkMaskFilter::FilterReturn
+SkBlurMaskFilterImpl::filterRRectToNine(const SkRRect& rrect, const SkMatrix& matrix,
+                                        const SkIRect& clipBounds,
+                                        NinePatch* patch) const {
+    SkASSERT(patch != NULL);
+    switch (rrect.getType()) {
+        case SkRRect::kUnknown_Type:
+            // Unknown should never be returned.
+            SkASSERT(false);
+            // Fall through.
+        case SkRRect::kEmpty_Type:
+            // Nothing to draw.
+            return kFalse_FilterReturn;
+
+        case SkRRect::kRect_Type:
+            // We should have caught this earlier.
+            SkASSERT(false);
+            // Fall through.
+        case SkRRect::kOval_Type:
+            // The nine patch special case does not handle ovals, and we
+            // already have code for rectangles.
+            return kUnimplemented_FilterReturn;
+
+        case SkRRect::kSimple_Type:
+            // Fall through.
+        case SkRRect::kComplex_Type:
+            // These can take advantage of this fast path.
+            break;
+    }
+
+    // TODO: report correct metrics for innerstyle, where we do not grow the
+    // total bounds, but we do need an inset the size of our blur-radius
+    if (SkBlurMaskFilter::kInner_BlurStyle == fBlurStyle) {
+        return kUnimplemented_FilterReturn;
+    }
+
+    // TODO: take clipBounds into account to limit our coordinates up front
+    // for now, just skip too-large src rects (to take the old code path).
+    if (rect_exceeds(rrect.rect(), SkIntToScalar(32767))) {
+        return kUnimplemented_FilterReturn;
+    }
+
+    SkIPoint margin;
+    SkMask  srcM, dstM;
+    rrect.rect().roundOut(&srcM.fBounds);
+    srcM.fImage = NULL;
+    srcM.fFormat = SkMask::kA8_Format;
+    srcM.fRowBytes = 0;
+
+    if (!this->filterMask(&dstM, srcM, matrix, &margin)) {
+        return kFalse_FilterReturn;
+    }
+
+    // Now figure out the appropriate width and height of the smaller round rectangle
+    // to stretch. It will take into account the larger radius per side as well as double
+    // the margin, to account for inner and outer blur.
+    const SkVector& UL = rrect.radii(SkRRect::kUpperLeft_Corner);

[reed1, 2013/11/04 17:46:52]

we're not calling the new allRadii API here...? (which is fine with me, since
I'm not convinced we should add it, but I am curious why we aren't).

[scroggo, 2013/11/04 19:52:54]

Really getAllRadii() is just a convenience for my call to setRectRadii(), where
I want to set to exactly the same values. Here I want to know about each set of
radii individually, so getAllRadii() provides no benefit.

+    const SkVector& UR = rrect.radii(SkRRect::kUpperRight_Corner);
+    const SkVector& LR = rrect.radii(SkRRect::kLowerRight_Corner);
+    const SkVector& LL = rrect.radii(SkRRect::kLowerLeft_Corner);
+
+    const SkScalar leftUnstretched = SkTMax(UL.fX, LL.fX) + SkIntToScalar(2 * margin.fX);
+    const SkScalar rightUnstretched = SkTMax(UR.fX, LR.fX) + SkIntToScalar(2 * margin.fX);
+
+    // Extra space in the middle to ensure an unchanging piece for stretching. Use 3 to cover
+    // any fractional space on either side plus 1 for the part to stretch.
+    const SkScalar stretchSize = SkIntToScalar(3);
+
+    const SkScalar totalSmallWidth = leftUnstretched + rightUnstretched + stretchSize;
+    if (totalSmallWidth >= rrect.rect().width()) {
+        // There is no valid piece to stretch.
+        return kUnimplemented_FilterReturn;
+    }
+
+    const SkScalar topUnstretched = SkTMax(UL.fY, UR.fY) + SkIntToScalar(2 * margin.fY);
+    const SkScalar bottomUnstretched = SkTMax(LL.fY, LR.fY) + SkIntToScalar(2 * margin.fY);
+
+    const SkScalar totalSmallHeight = topUnstretched + bottomUnstretched + stretchSize;
+    if (totalSmallHeight >= rrect.rect().height()) {
+        // There is no valid piece to stretch.
+        return kUnimplemented_FilterReturn;
+    }
+
+    SkRect smallR = SkRect::MakeWH(totalSmallWidth, totalSmallHeight);
+
+    SkRRect smallRR;
+    smallRR.setRectRadii(smallR, rrect.getAllRadii());
+
+    if (!draw_rrect_into_mask(smallRR, &srcM)) {
+        return kFalse_FilterReturn;
+    }
+
+    if (!this->filterMask(&patch->fMask, srcM, matrix, &margin)) {
+        return kFalse_FilterReturn;
+    }
+
+    patch->fMask.fBounds.offsetTo(0, 0);
+    patch->fOuterRect = dstM.fBounds;
+    patch->fCenter.fX = SkScalarCeilToInt(leftUnstretched) + 1;
+    patch->fCenter.fY = SkScalarCeilToInt(topUnstretched) + 1;
+    return kTrue_FilterReturn;
+}
+
 #ifdef SK_IGNORE_FAST_RECT_BLUR
 SK_CONF_DECLARE( bool, c_analyticBlurNinepatch, "mask.filter.analyticNinePatch", false, "Use the faster analytic blur approach for ninepatch rects" );
 #else