Initial support for turning Skia draws into a JSON document and vice versa.

tools/json/SkJSONRenderer.cpp

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkJSONRenderer.h"
+#include "SkJSONCanvas.h"
+#include "SkJSONCPP.h"
+#include "SkPath.h"
+
+namespace SkJSONRenderer {
+
+class Renderer {
+public:
+    void getPaint(Json::Value& command, SkPaint* paint);
+
+    void getRect(Json::Value& command, const char* name, SkRect* rect);
+
+    void getRRect(Json::Value& command, const char* name, SkRRect* rrect);
+
+    void processCommand(Json::Value& command, SkCanvas* target);
+
+    void processMatrix(Json::Value& command, SkCanvas* target);
+
+    void processSave(Json::Value& command, SkCanvas* target);
+
+    void processRestore(Json::Value& command, SkCanvas* target);
+
+    void processPaint(Json::Value& command, SkCanvas* target);
+
+    void processRect(Json::Value& command, SkCanvas* target);
+
+    void processRRect(Json::Value& command, SkCanvas* target);
+
+    void processOval(Json::Value& command, SkCanvas* target);
+
+    void processPath(Json::Value& command, SkCanvas* target);
+
+    void processText(Json::Value& command, SkCanvas* target);
+
+    void processPoints(Json::Value& command, SkCanvas* target);
+
+    void processClipRect(Json::Value& command, SkCanvas* target);
+};
+
+void Renderer::processCommand(Json::Value& command, SkCanvas* target) {
+    const char* name = command[SKJSONCANVAS_COMMAND].asCString();
+    // TODO speed this up with a hash
+    if (!strcmp(name, SKJSONCANVAS_COMMAND_MATRIX)) {
+        this->processMatrix(command, target);
+    }
+    else if (!strcmp(name, SKJSONCANVAS_COMMAND_SAVE)) {
+        this->processSave(command, target);
+    }
+    else if (!strcmp(name, SKJSONCANVAS_COMMAND_RESTORE)) {
+        this->processRestore(command, target);
+    }
+    else if (!strcmp(name, SKJSONCANVAS_COMMAND_PAINT)) {
+        this->processPaint(command, target);
+    }
+    else if (!strcmp(name, SKJSONCANVAS_COMMAND_RECT)) {
+        this->processRect(command, target);
+    }
+    else if (!strcmp(name, SKJSONCANVAS_COMMAND_RRECT)) {
+        this->processRRect(command, target);
+    }
+    else if (!strcmp(name, SKJSONCANVAS_COMMAND_OVAL)) {
+        this->processOval(command, target);
+    }
+    else if (!strcmp(name, SKJSONCANVAS_COMMAND_PATH)) {
+        this->processPath(command, target);
+    }
+    else if (!strcmp(name, SKJSONCANVAS_COMMAND_TEXT)) {
+        this->processText(command, target);
+    }
+    else if (!strcmp(name, SKJSONCANVAS_COMMAND_POINTS)) {
+        this->processPoints(command, target);
+    }
+    else if (!strcmp(name, SKJSONCANVAS_COMMAND_CLIPRECT)) {
+        this->processClipRect(command, target);
+    }
+    else {
+        SkDebugf("unsupported JSON command: %s\n", name);
+    }
+}
+
+void Renderer::getPaint(Json::Value& command, SkPaint* result) {
+    Json::Value jsonPaint = command[SKJSONCANVAS_ATTRIBUTE_PAINT];
+    if (jsonPaint.isMember(SKJSONCANVAS_ATTRIBUTE_COLOR)) {
+        Json::Value color = jsonPaint[SKJSONCANVAS_ATTRIBUTE_COLOR];
+        result->setColor(SkColorSetARGB(color[0].asInt(), color[1].asInt(), color[2].asInt(),
+                         color[3].asInt()));
+    }
+    if (jsonPaint.isMember(SKJSONCANVAS_ATTRIBUTE_STYLE)) {
+        const char* style = jsonPaint[SKJSONCANVAS_ATTRIBUTE_STYLE].asCString();
+        if (!strcmp(style, SKJSONCANVAS_STYLE_FILL)) {
+            result->setStyle(SkPaint::kFill_Style);
+        }
+        else if (!strcmp(style, SKJSONCANVAS_STYLE_STROKE)) {
+            result->setStyle(SkPaint::kStroke_Style);
+        }
+        else if (!strcmp(style, SKJSONCANVAS_STYLE_STROKEANDFILL)) {
+            result->setStyle(SkPaint::kStrokeAndFill_Style);
+        }
+    }
+    if (jsonPaint.isMember(SKJSONCANVAS_ATTRIBUTE_STROKEWIDTH)) {
+        float strokeWidth = jsonPaint[SKJSONCANVAS_ATTRIBUTE_STROKEWIDTH].asFloat();
+        result->setStrokeWidth(strokeWidth);
+    }
+    if (jsonPaint.isMember(SKJSONCANVAS_ATTRIBUTE_ANTIALIAS)) {
+        result->setAntiAlias(jsonPaint[SKJSONCANVAS_ATTRIBUTE_ANTIALIAS].asBool());
+    }
+}
+
+void Renderer::getRect(Json::Value& command, const char* name, SkRect* result) {
+    Json::Value rect = command[name];
+    result->set(rect[0].asFloat(), rect[1].asFloat(), rect[2].asFloat(), rect[3].asFloat());
+}
+
+void Renderer::getRRect(Json::Value& command, const char* name, SkRRect* result) {
+    Json::Value rrect = command[name];
+    SkVector radii[4] = {
+                            { rrect[1][0].asFloat(), rrect[1][1].asFloat() }, 
+                            { rrect[2][0].asFloat(), rrect[2][1].asFloat() }, 
+                            { rrect[3][0].asFloat(), rrect[3][1].asFloat() }, 
+                            { rrect[4][0].asFloat(), rrect[4][1].asFloat() }
+                        };
+    result->setRectRadii(SkRect::MakeLTRB(rrect[0][0].asFloat(), rrect[0][1].asFloat(), 
+                                          rrect[0][2].asFloat(), rrect[0][3].asFloat()), 
+                         radii);
+}
+
+void Renderer::processMatrix(Json::Value& command, SkCanvas* target) {
+    Json::Value jsonMatrix = command[SKJSONCANVAS_ATTRIBUTE_MATRIX];
+    SkMatrix matrix;
+    SkScalar values[] = { 
+        jsonMatrix[0][0].asFloat(), jsonMatrix[0][1].asFloat(), jsonMatrix[0][2].asFloat(),
+        jsonMatrix[1][0].asFloat(), jsonMatrix[1][1].asFloat(), jsonMatrix[1][2].asFloat(),
+        jsonMatrix[2][0].asFloat(), jsonMatrix[2][1].asFloat(), jsonMatrix[2][2].asFloat() 
+    };
+    matrix.set9(values);
+    target->setMatrix(matrix);
+}
+
+void Renderer::processSave(Json::Value& command, SkCanvas* target) {
+    target->save();
+}
+
+void Renderer::processRestore(Json::Value& command, SkCanvas* target) {
+    target->restore();
+}
+
+void Renderer::processPaint(Json::Value& command, SkCanvas* target) {
+    SkPaint paint;
+    this->getPaint(command, &paint);
+    target->drawPaint(paint);
+}
+
+void Renderer::processRect(Json::Value& command, SkCanvas* target) {
+    SkRect rect;
+    this->getRect(command, SKJSONCANVAS_ATTRIBUTE_COORDS, &rect);
+    SkPaint paint;
+    this->getPaint(command, &paint);
+    target->drawRect(rect, paint);
+}
+
+void Renderer::processRRect(Json::Value& command, SkCanvas* target) {
+    SkRRect rrect;
+    this->getRRect(command, SKJSONCANVAS_ATTRIBUTE_COORDS, &rrect);
+    SkPaint paint;
+    this->getPaint(command, &paint);
+    target->drawRRect(rrect, paint);
+}
+
+void Renderer::processOval(Json::Value& command, SkCanvas* target) {
+    SkRect rect;
+    this->getRect(command, SKJSONCANVAS_ATTRIBUTE_COORDS, &rect);
+    SkPaint paint;
+    this->getPaint(command, &paint);
+    target->drawOval(rect, paint);
+}
+
+void Renderer::processPath(Json::Value& command, SkCanvas* target) {
+    Json::Value jsonPath = command[SKJSONCANVAS_ATTRIBUTE_PATH];
+    SkPath path;
+    for (Json::ArrayIndex i = 0; i < jsonPath.size(); i++) {
+        Json::Value verb = jsonPath[i];
+        if (verb.isString()) {
+            SkASSERT(!strcmp(verb.asCString(), SKJSONCANVAS_VERB_CLOSE));
+            path.close();
+        }
+        else {
+            if (verb.isMember(SKJSONCANVAS_VERB_MOVE)) {
+                Json::Value move = verb[SKJSONCANVAS_VERB_MOVE];
+                path.moveTo(move[0].asFloat(), move[1].asFloat());
+            }
+            else if (verb.isMember(SKJSONCANVAS_VERB_LINE)) {
+                Json::Value line = verb[SKJSONCANVAS_VERB_LINE];
+                path.lineTo(line[0].asFloat(), line[1].asFloat());
+            }
+            else if (verb.isMember(SKJSONCANVAS_VERB_QUAD)) {
+                Json::Value quad = verb[SKJSONCANVAS_VERB_QUAD];
+                path.quadTo(quad[0][0].asFloat(), quad[0][1].asFloat(),
+                            quad[1][0].asFloat(), quad[1][1].asFloat());
+            }
+            else if (verb.isMember(SKJSONCANVAS_VERB_CUBIC)) {
+                Json::Value cubic = verb[SKJSONCANVAS_VERB_CUBIC];
+                path.cubicTo(cubic[0][0].asFloat(), cubic[0][1].asFloat(),
+                             cubic[1][0].asFloat(), cubic[1][1].asFloat(),
+                             cubic[2][0].asFloat(), cubic[2][1].asFloat());
+            }
+            else if (verb.isMember(SKJSONCANVAS_VERB_CONIC)) {
+                Json::Value conic = verb[SKJSONCANVAS_VERB_CONIC];
+                path.conicTo(conic[0][0].asFloat(), conic[0][1].asFloat(),
+                             conic[1][0].asFloat(), conic[1][1].asFloat(),
+                             conic[2].asFloat());
+            }
+            else {
+                SkASSERT(false);
+            }
+        }
+    }
+    SkPaint paint;
+    this->getPaint(command, &paint);
+    target->drawPath(path, paint);
+}
+
+void Renderer::processText(Json::Value& command, SkCanvas* target) {
+    const char* text = command[SKJSONCANVAS_ATTRIBUTE_TEXT].asCString();
+    SkPaint paint;
+    this->getPaint(command, &paint);
+    Json::Value coords = command[SKJSONCANVAS_ATTRIBUTE_COORDS];
+    target->drawText(text, strlen(text), coords[0].asFloat(), coords[1].asFloat(), paint);
+}
+
+void Renderer::processPoints(Json::Value& command, SkCanvas* target) {
+    SkCanvas::PointMode mode;
+    const char* jsonMode = command[SKJSONCANVAS_ATTRIBUTE_MODE].asCString();
+    if (!strcmp(jsonMode, SKJSONCANVAS_POINTMODE_POINTS)) {
+        mode = SkCanvas::kPoints_PointMode;
+    }
+    else if (!strcmp(jsonMode, SKJSONCANVAS_POINTMODE_LINES)) {
+        mode = SkCanvas::kLines_PointMode;
+    }
+    else if (!strcmp(jsonMode, SKJSONCANVAS_POINTMODE_POLYGON)) {
+        mode = SkCanvas::kPolygon_PointMode;
+    }
+    else {
+        SkASSERT(false);
+        return;
+    }
+    Json::Value jsonPoints = command[SKJSONCANVAS_ATTRIBUTE_POINTS];
+    int count = (int) jsonPoints.size();
+    SkPoint* points = (SkPoint*) sk_malloc_throw(count * sizeof(SkPoint));
+    for (int i = 0; i < count; i++) {
+        points[i] = SkPoint::Make(jsonPoints[i][0].asFloat(), jsonPoints[i][1].asFloat());
+    }
+    SkPaint paint;
+    this->getPaint(command, &paint);
+    target->drawPoints(mode, count, points, paint);
+    free(points);
+}
+
+void Renderer::processClipRect(Json::Value& command, SkCanvas* target) {
+    SkRect rect;
+    this->getRect(command, SKJSONCANVAS_ATTRIBUTE_COORDS, &rect);
+    target->clipRect(rect);
+}
+
+void render(const char* json, SkCanvas* target) {
+    Renderer renderer;
+    Json::Reader reader;
+    Json::Value root;
+    if (reader.parse(std::string(json), root)) {
+        SkASSERT(root[SKJSONCANVAS_VERSION].asInt() == 1);
+        Json::Value commands = root[SKJSONCANVAS_COMMANDS];
+        for (Json::ArrayIndex i = 0; i < commands.size(); i++) {
+            renderer.processCommand(commands[i], target);
+        }
+    }
+    else {
+        SkDebugf(json);
+        SkFAIL("json parse failure");
+    }
+}
+
+} // namespace