Add animated line chart sample
R=robertphillips@google.com
Review URL: https://codereview.appspot.com/7307117
git-svn-id: http://skia.googlecode.com/svn/trunk@7727 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleChart.cpp b/samplecode/SampleChart.cpp
new file mode 100644
index 0000000..68d750f
--- /dev/null
+++ b/samplecode/SampleChart.cpp
@@ -0,0 +1,188 @@
+
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "SampleCode.h"
+#include "SkCanvas.h"
+#include "SkPaint.h"
+#include "SkRandom.h"
+#include "SkView.h"
+
+namespace {
+
+// Generates y values for the chart plots.
+void gen_data(SkScalar yAvg, SkScalar ySpread, int count, SkTDArray<SkScalar>* dataPts) {
+ dataPts->setCount(count);
+ static SkMWCRandom gRandom;
+ for (int i = 0; i < count; ++i) {
+ (*dataPts)[i] = gRandom.nextRangeScalar(yAvg - SkScalarHalf(ySpread),
+ yAvg + SkScalarHalf(ySpread));
+ }
+}
+
+// Generates a path to stroke along the top of each plot and a fill path for the area below each
+// plot. The fill path is bounded below by the bottomData plot points or a horizontal line at
+// yBase if bottomData == NULL.
+// The plots are animated by rotating the data points by leftShift.
+void gen_paths(const SkTDArray<SkScalar>& topData,
+ const SkTDArray<SkScalar>* bottomData,
+ SkScalar yBase,
+ SkScalar xLeft, SkScalar xDelta,
+ int leftShift,
+ SkPath* plot, SkPath* fill) {
+ plot->rewind();
+ fill->rewind();
+ plot->incReserve(topData.count());
+ if (NULL == bottomData) {
+ fill->incReserve(topData.count() + 2);
+ } else {
+ fill->incReserve(2 * topData.count());
+ }
+
+ leftShift %= topData.count();
+ SkScalar x = xLeft;
+
+ // Account for the leftShift using two loops
+ int shiftToEndCount = topData.count() - leftShift;
+ plot->moveTo(x, topData[leftShift]);
+ fill->moveTo(x, topData[leftShift]);
+
+ for (int i = 1; i < shiftToEndCount; ++i) {
+ plot->lineTo(x, topData[i + leftShift]);
+ fill->lineTo(x, topData[i + leftShift]);
+ x += xDelta;
+ }
+
+ for (int i = 0; i < leftShift; ++i) {
+ plot->lineTo(x, topData[i]);
+ fill->lineTo(x, topData[i]);
+ x += xDelta;
+ }
+
+ if (NULL != bottomData) {
+ SkASSERT(bottomData->count() == topData.count());
+ // iterate backwards over the previous graph's data to generate the bottom of the filled
+ // area (and account for leftShift).
+ for (int i = 0; i < leftShift; ++i) {
+ x -= xDelta;
+ fill->lineTo(x, (*bottomData)[leftShift - 1 - i]);
+ }
+ for (int i = 0; i < shiftToEndCount; ++i) {
+ x -= xDelta;
+ fill->lineTo(x, (*bottomData)[bottomData->count() - 1 - i]);
+ }
+ } else {
+ fill->lineTo(x - xDelta, yBase);
+ fill->lineTo(xLeft, yBase);
+ }
+}
+
+}
+
+// A set of scrolling line plots with the area between each plot filled. Stresses out GPU path
+// filling
+class ChartView : public SampleView {
+public:
+ ChartView() {
+ fShift = 0;
+ fSize.set(-1, -1);
+ }
+
+protected:
+ virtual bool onQuery(SkEvent* evt) SK_OVERRIDE {
+ if (SampleCode::TitleQ(*evt)) {
+ SampleCode::TitleR(evt, "Chart");
+ return true;
+ }
+ return this->INHERITED::onQuery(evt);
+ }
+
+ virtual void onDrawContent(SkCanvas* canvas) SK_OVERRIDE {
+ bool sizeChanged = false;
+ if (canvas->getDeviceSize() != fSize) {
+ fSize = canvas->getDeviceSize();
+ sizeChanged = true;
+ }
+
+ SkScalar ySpread = SkIntToScalar(fSize.fHeight / 20);
+
+ SkScalar height = SkIntToScalar(fSize.fHeight);
+
+ if (sizeChanged) {
+ int dataPointCount = SkMax32(fSize.fWidth / kPixelsPerTick + 1, 2);
+
+ for (int i = 0; i < kNumGraphs; ++i) {
+ SkScalar y = (kNumGraphs - i) * (height - ySpread) / (kNumGraphs + 1);
+ fData[i].reset();
+ gen_data(y, ySpread, dataPointCount, fData + i);
+ }
+ }
+
+ canvas->clear(0xFFE0F0E0);
+
+ static SkMWCRandom colorRand;
+ static SkColor gColors[kNumGraphs] = { 0x0 };
+ if (0 == gColors[0]) {
+ for (int i = 0; i < kNumGraphs; ++i) {
+ gColors[i] = colorRand.nextU() | 0xff000000;
+ }
+ }
+
+ SkPath plotPath;
+ SkPath fillPath;
+
+ static const SkScalar kStrokeWidth = SkIntToScalar(2);
+ SkPaint plotPaint;
+ SkPaint fillPaint;
+ plotPaint.setAntiAlias(true);
+ plotPaint.setStyle(SkPaint::kStroke_Style);
+ plotPaint.setStrokeWidth(kStrokeWidth);
+ plotPaint.setStrokeCap(SkPaint::kRound_Cap);
+ plotPaint.setStrokeJoin(SkPaint::kRound_Join);
+ fillPaint.setAntiAlias(true);
+ fillPaint.setStyle(SkPaint::kFill_Style);
+
+ SkTDArray<SkScalar>* prevData = NULL;
+ for (int i = 0; i < kNumGraphs; ++i) {
+ gen_paths(fData[i],
+ prevData,
+ height,
+ 0,
+ SkIntToScalar(kPixelsPerTick),
+ fShift,
+ &plotPath,
+ &fillPath);
+
+ // Make the fills partially transparent
+ fillPaint.setColor((gColors[i] & 0x00ffffff) | 0x80000000);
+ canvas->drawPath(fillPath, fillPaint);
+
+ plotPaint.setColor(gColors[i]);
+ canvas->drawPath(plotPath, plotPaint);
+
+ prevData = fData + i;
+ }
+
+ fShift += kShiftPerFrame;
+ this->inval(NULL);
+ }
+
+private:
+ enum {
+ kNumGraphs = 5,
+ kPixelsPerTick = 3,
+ kShiftPerFrame = 1,
+ };
+ int fShift;
+ SkISize fSize;
+ SkTDArray<SkScalar> fData[kNumGraphs];
+ typedef SampleView INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static SkView* MyFactory() { return new ChartView; }
+static SkViewRegister reg(MyFactory);