Get OffsetImageFilter really working with SkSpecialImages

src/effects/SkOffsetImageFilter.cpp

 /*
  * Copyright 2012 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkOffsetImageFilter.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkDevice.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkMatrix.h"
 #include "SkPaint.h"
+#include "SkSpecialImage.h"
+#include "SkSpecialSurface.h"
+
+SkSpecialImage* SkOffsetImageFilter::onFilterImage(SkSpecialImage* srcIn,
+                                                   const Context& ctx,
+                                                   SkIPoint* offset) const {
+    SkIPoint srcOffset = SkIPoint::Make(0, 0);
+    SkAutoTUnref<SkSpecialImage> src(this->filterInput(0, srcIn, ctx, &srcOffset));
+    if (!src) {
+        return nullptr;
+    }
+
+    SkVector vec;
+    ctx.ctm().mapVectors(&vec, &fOffset, 1);
+
+    if (!this->cropRectIsSet()) {
+        offset->fX = srcOffset.fX + SkScalarRoundToInt(vec.fX);
+        offset->fY = srcOffset.fY + SkScalarRoundToInt(vec.fY);
+        return src.release();
+    } else {
+        SkIRect bounds;
+        SkIRect srcBounds = SkIRect::MakeWH(srcIn->width(), srcIn->height());
+        srcBounds.offset(srcOffset);
+        if (!this->applyCropRect(ctx, srcBounds, &bounds)) {
+            return false;
+        }
+
+        SkImageInfo info = SkImageInfo::MakeN32(bounds.width(), bounds.height(),
+                                                kPremul_SkAlphaType);
+        // TODO: need to plumb MSAA sampleCount down to here!

[Stephen White, 2016/02/18 17:56:18]

I don't think we should (except for the original primitive drawn by saveLayer,
which doesn't go through this path), but I might be missing a special case.

Maybe we should just remove this comment and keep an eye on the GM results?

[robertphillips, 2016/02/19 19:37:59]

Done. I agree that all the draws performed by the image filters shouldn't need
MSAA.

+        SkAutoTUnref<SkSpecialSurface> surf(src->newSurface(info));
+        if (!surf) {
+            return nullptr;
+        }
+
+        SkCanvas* canvas = surf->getCanvas();
+
+        canvas->clear(0x0);
+
+        SkPaint paint;
+        paint.setXfermodeMode(SkXfermode::kSrc_Mode);
+        canvas->translate(SkIntToScalar(srcOffset.fX - bounds.fLeft),
+                          SkIntToScalar(srcOffset.fY - bounds.fTop));
+
+        src->draw(canvas, vec.x(), vec.y(), &paint);
+
+        offset->fX = bounds.fLeft;
+        offset->fY = bounds.fTop;
+        return surf->newImageSnapshot();
+    }
+}
 
 bool SkOffsetImageFilter::onFilterImageDeprecated(Proxy* proxy, const SkBitmap& source,

[Stephen White, 2016/02/18 17:56:18]

Can we not simply remove this function now? When does this get called?

[robertphillips, 2016/02/19 19:37:59]

It can still be called when the offset image filter is the root of the DAG
(e.g., from within SkCanvas::internalDrawDevice).

[Stephen White, 2016/02/19 19:53:55]

Could we also switch over the callsites (in SkCanvas and SkGpuDevice) to use
filterImage() in this patch? Then we should be able to remove the legacy path
from each filter as we go. Would that work?

[robertphillips, 2016/02/22 15:21:58]

I think that should probably be its own patch. We could land the SkImageFilter.*
changes, then that patch, then a revised version of the SkOffsetImageFilter.*
files.

[Stephen White, 2016/02/22 15:42:38]

OK, just to clarify: you're saying

1) Land the SkImageFilter.* changes from this patch
2) Land the infrastructure patch (SkCanvas/SkGpuDevice)
3) Land the (updated) SkOffsetImageFilter changes from this patch
*) Convert the remaining filters

?

If so, I'm good with that.

                                                   const Context& ctx,
                                                   SkBitmap* result,
                                                   SkIPoint* offset) const {
-    SkBitmap src = source;
-    SkIPoint srcOffset = SkIPoint::Make(0, 0);
-    if (!cropRectIsSet()) {
-        if (!this->filterInputDeprecated(0, proxy, source, ctx, &src, &srcOffset)) {
-            return false;
-        }
+    SkAutoTUnref<SkSpecialImage> specialSrc(SkSpecialImage::internal_fromBM(proxy, source));
+    if (!specialSrc) {
+        return false;
+    }
 
-        SkVector vec;
-        ctx.ctm().mapVectors(&vec, &fOffset, 1);
+    SkAutoTUnref<SkSpecialImage> tmp(this->onFilterImage(specialSrc, ctx, offset));
+    if (!tmp) {
+        return false;
+    }
 
-        offset->fX = srcOffset.fX + SkScalarRoundToInt(vec.fX);
-        offset->fY = srcOffset.fY + SkScalarRoundToInt(vec.fY);
-        *result = src;
-    } else {
-        if (!this->filterInputDeprecated(0, proxy, source, ctx, &src, &srcOffset)) {
-            return false;
-        }
-
-        SkIRect bounds;
-        SkIRect srcBounds = src.bounds();
-        srcBounds.offset(srcOffset);
-        if (!this->applyCropRect(ctx, srcBounds, &bounds)) {
-            return false;
-        }
-
-        SkAutoTUnref<SkBaseDevice> device(proxy->createDevice(bounds.width(), bounds.height()));
-        if (nullptr == device.get()) {
-            return false;
-        }
-        SkCanvas canvas(device);
-        SkPaint paint;
-        paint.setXfermodeMode(SkXfermode::kSrc_Mode);
-        canvas.translate(SkIntToScalar(srcOffset.fX - bounds.fLeft),
-                         SkIntToScalar(srcOffset.fY - bounds.fTop));
-        SkVector vec;
-        ctx.ctm().mapVectors(&vec, &fOffset, 1);
-        canvas.drawBitmap(src, vec.x(), vec.y(), &paint);
-        *result = device->accessBitmap(false);
-        offset->fX = bounds.fLeft;
-        offset->fY = bounds.fTop;
-    }
-    return true;
+    return tmp->internal_getBM(result);
 }
 
 void SkOffsetImageFilter::computeFastBounds(const SkRect& src, SkRect* dst) const {
     if (getInput(0)) {
         getInput(0)->computeFastBounds(src, dst);
     } else {
         *dst = src;
     }
     dst->offset(fOffset.fX, fOffset.fY);
 }
@@ skipping 32 matching lines @@
 void SkOffsetImageFilter::toString(SkString* str) const {
     str->appendf("SkOffsetImageFilter: (");
     str->appendf("offset: (%f, %f) ", fOffset.fX, fOffset.fY);
     str->append("input: (");
     if (this->getInput(0)) {
         this->getInput(0)->toString(str);
     }
     str->append("))");
 }
 #endif