commit c55c8c1e8e3de05bdd43f76e6e3582fec04c35ba
author Florin Malita <fmalita@chromium.org> Mon Jan 25 10:37:22 2021 -0500
committer Skia Commit-Bot <skia-commit-bot@chromium.org> Mon Jan 25 16:40:16 2021 +0000
tree fec82218bc309396f5627bd04bef0c2e0016b373
parent bd91660b6e12640c6c3e3fe53e21acd8dd512b41

[svg] Generalize text shaping

In preparation for text bounding box support, fission the actual
rendering phase from the shaping/alignment phase:

  - rename onRenderText -> onShapeText
  - introduce a ShapedTextCallback abstraction for consuming the result
    of text processing
  - relocate the final rendering step to a ShapedTextCallback impl

Bug: skia:10840
Change-Id: Ia8cc0d9a5a5484972a34042fd782f9e4fada6b12
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/358223
Commit-Queue: Florin Malita <fmalita@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Tyler Denniston <tdenniston@google.com>

modules/svg/src/SkSVGText.cpp

diff --git a/modules/svg/src/SkSVGText.cpp b/modules/svg/src/SkSVGText.cpp
index 7b25578..f81eb7c 100644
--- a/modules/svg/src/SkSVGText.cpp
+++ b/modules/svg/src/SkSVGText.cpp
@@ -223,8 +223,10 @@
     fShapeBuffer.reset();
 }
 
-SkSVGTextContext::SkSVGTextContext(const SkSVGRenderContext& ctx, const SkSVGTextPath* tpath)
+SkSVGTextContext::SkSVGTextContext(const SkSVGRenderContext& ctx, const ShapedTextCallback& cb,
+                                   const SkSVGTextPath* tpath)
     : fRenderContext(ctx)
+    , fCallback(cb)
     , fShaper(SkShaper::Make(ctx.fontMgr()))
     , fChunkAlignmentFactor(ComputeAlignmentFactor(ctx.presentationContext()))
 {
@@ -255,8 +257,8 @@
     this->flushChunk(fRenderContext);
 }
 
-void SkSVGTextContext::appendFragment(const SkString& txt, const SkSVGRenderContext& ctx,
-                                      SkSVGXmlSpace xs) {
+void SkSVGTextContext::shapeFragment(const SkString& txt, const SkSVGRenderContext& ctx,
+                                     SkSVGXmlSpace xs) {
     // https://www.w3.org/TR/SVG11/text.html#WhiteSpace
     // https://www.w3.org/TR/2008/REC-xml-20081126/#NT-S
     auto filterWSDefault = [this](SkUnichar ch) -> SkUnichar {
@@ -417,15 +419,7 @@
                                                       run.glyhPosAdjust[i]);
         }
 
-        // Technically, blobs with compatible paints could be merged --
-        // but likely not worth the effort.
-        const auto blob = blobBuilder.make();
-        if (run.fillPaint) {
-            ctx.canvas()->drawTextBlob(blob, 0, 0, *run.fillPaint);
-        }
-        if (run.strokePaint) {
-            ctx.canvas()->drawTextBlob(blob, 0, 0, *run.strokePaint);
-        }
+        fCallback(ctx, blobBuilder.make(), run.fillPaint.get(), run.strokePaint.get());
     }
 
     fChunkPos += fChunkAdvance;
@@ -480,7 +474,7 @@
     SkSVGRenderContext localContext(ctx, this);
 
     if (this->onPrepareToRender(&localContext)) {
-        this->onRenderText(localContext, tctx, xs);
+        this->onShapeText(localContext, tctx, xs);
     }
 }
 
@@ -503,8 +497,8 @@
     }
 }
 
-void SkSVGTextContainer::onRenderText(const SkSVGRenderContext& ctx, SkSVGTextContext* tctx,
-                                      SkSVGXmlSpace) const {
+void SkSVGTextContainer::onShapeText(const SkSVGRenderContext& ctx, SkSVGTextContext* tctx,
+                                     SkSVGXmlSpace) const {
     SkASSERT(tctx);
 
     const SkSVGTextContext::ScopedPosResolver resolver(*this, ctx.lengthContext(), tctx);
@@ -538,26 +532,40 @@
            this->setXmlSpace(SkSVGAttributeParser::parse<SkSVGXmlSpace>("xml:space", name, value));
 }
 
-void SkSVGTextLiteral::onRenderText(const SkSVGRenderContext& ctx, SkSVGTextContext* tctx,
-                                    SkSVGXmlSpace xs) const {
+void SkSVGTextLiteral::onShapeText(const SkSVGRenderContext& ctx, SkSVGTextContext* tctx,
+                                   SkSVGXmlSpace xs) const {
     SkASSERT(tctx);
 
-    tctx->appendFragment(this->getText(), ctx, xs);
+    tctx->shapeFragment(this->getText(), ctx, xs);
 }
 
 void SkSVGText::onRender(const SkSVGRenderContext& ctx) const {
-    // Root <text> nodes establish a text layout context.
-    SkSVGTextContext tctx(ctx);
+    const SkSVGTextContext::ShapedTextCallback render_text = [](const SkSVGRenderContext& ctx,
+                                                                const sk_sp<SkTextBlob>& blob,
+                                                                const SkPaint* fill,
+                                                                const SkPaint* stroke) {
+        if (fill) {
+            ctx.canvas()->drawTextBlob(blob, 0, 0, *fill);
+        }
+        if (stroke) {
+            ctx.canvas()->drawTextBlob(blob, 0, 0, *stroke);
+        }
+    };
 
-    this->onRenderText(ctx, &tctx, this->getXmlSpace());
+    // Root <text> nodes establish a text layout context.
+    SkSVGTextContext tctx(ctx, render_text);
+
+    this->onShapeText(ctx, &tctx, this->getXmlSpace());
 }
 
-void SkSVGTextPath::onRenderText(const SkSVGRenderContext& ctx, SkSVGTextContext*,
+void SkSVGTextPath::onShapeText(const SkSVGRenderContext& ctx, SkSVGTextContext* parent_tctx,
                                  SkSVGXmlSpace xs) const {
-    // textPath nodes establish a new text layout context.
-    SkSVGTextContext tctx(ctx, this);
+    SkASSERT(parent_tctx);
 
-    this->INHERITED::onRenderText(ctx, &tctx, xs);
+    // textPath nodes establish a new text layout context.
+    SkSVGTextContext tctx(ctx, parent_tctx->getCallback(), this);
+
+    this->INHERITED::onShapeText(ctx, &tctx, xs);
 }
 
 bool SkSVGTextPath::parseAndSetAttribute(const char* name, const char* value) {