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/*
* 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"
// Generates y values for the chart plots.
static void gen_data(SkScalar yAvg, SkScalar ySpread, int count, SkTDArray<SkScalar>* dataPts) {
dataPts->setCount(count);
static SkRandom 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.
static 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 SkRandom 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);
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