this change improves the following points of the FPS counter:

-cleaner design: less colors, text arranged above the graph, deviation number right aligned 
-added transparency: FPS counter does not completely cover the webpage
-less frequent number updates: makes the numbers easier to read
-indicator line at 60fps

comparison images: https://docs.google.com/folder/d/0B8Y78t3tjy1XZk1xdWx6VjN5aFE/edit

Please download the patch and provide a screenshot from your system to test the layout.

Review URL: https://chromiumcodereview.appspot.com/11272042

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@166041 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 152 insertions, 90 deletions

diff --git a/cc/font_atlas.cc b/cc/font_atlas.cc
index 2d15766..099e7f0 100644
--- a/cc/font_atlas.cc
+++ b/cc/font_atlas.cc
@@ -57,6 +57,25 @@ void FontAtlas::drawOneLineOfTextInternal(SkCanvas* canvas, const SkPaint& paint
     }
 }
 
+gfx::Size FontAtlas::textSize(const std::string& text)
+{
+    int maxWidth = 0;
+    std::vector<std::string> lines;
+    base::SplitString(text, '\n', &lines);
+
+    for (size_t i = 0; i < lines.size(); ++i) {
+        int lineWidth = 0;
+        for (size_t j = 0; j < lines[i].size(); ++j) {
+            int asciiIndex = (lines[i][j] < 128) ? lines[i][j] : 0;
+            lineWidth += m_asciiToRectTable[asciiIndex].width();
+        }
+        if (lineWidth > maxWidth)
+            maxWidth = lineWidth;
+    }
+
+    return gfx::Size(maxWidth, m_fontHeight * lines.size());
+}
+
 void FontAtlas::drawDebugAtlas(SkCanvas* canvas, const gfx::Point& destPosition) const
 {
     DCHECK(Proxy::isImplThread());
diff --git a/cc/font_atlas.h b/cc/font_atlas.h
index 24592e4..d18483f 100644
--- a/cc/font_atlas.h
+++ b/cc/font_atlas.h
@@ -31,6 +31,9 @@ public:
     }
     ~FontAtlas();
 
+    // Current font height.
+    int fontHeight() const { return m_fontHeight; }
+
     // Draws multiple lines of text where each line of text is separated by '\n'.
     // - Correct glyphs will be drawn for ASCII codes in the range 32-127; any characters
     //   outside that range will be displayed as a default rectangle glyph.
@@ -39,6 +42,9 @@ public:
     // - Should only be called only on the impl thread.
     void drawText(SkCanvas*, const SkPaint&, const std::string& text, const gfx::Point& destPosition, const gfx::Size& clip) const;
 
+    // Gives a text's width and height on the canvas.
+    gfx::Size textSize(const std::string& text);
+
     // Draws the entire atlas at the specified position, just for debugging purposes.
     void drawDebugAtlas(SkCanvas*, const gfx::Point& destPosition) const;
 
diff --git a/cc/frame_rate_counter.cc b/cc/frame_rate_counter.cc
index 585dee7..fca42a5 100644
--- a/cc/frame_rate_counter.cc
+++ b/cc/frame_rate_counter.cc
@@ -70,9 +70,10 @@ void FrameRateCounter::markEndOfFrame()
 
 bool FrameRateCounter::isBadFrameInterval(base::TimeDelta intervalBetweenConsecutiveFrames) const
 {
+    double delta = intervalBetweenConsecutiveFrames.InSecondsF();
     bool schedulerAllowsDoubleFrames = !Proxy::hasImplThread();
-    bool intervalTooFast = schedulerAllowsDoubleFrames && intervalBetweenConsecutiveFrames.InSecondsF() < kFrameTooFast;
-    bool intervalTooSlow = intervalBetweenConsecutiveFrames.InSecondsF() > kFrameTooSlow;
+    bool intervalTooFast = schedulerAllowsDoubleFrames ? delta < kFrameTooFast : delta <= 0.0;
+    bool intervalTooSlow = delta > kFrameTooSlow;
     return intervalTooFast || intervalTooSlow;
 }
 
@@ -83,11 +84,13 @@ bool FrameRateCounter::isBadFrame(int frameNumber) const
 
 void FrameRateCounter::getAverageFPSAndStandardDeviation(double& averageFPS, double& standardDeviation) const
 {
-    int frame = m_currentFrameNumber - 1;
-    averageFPS = 0;
-    int averageFPSCount = 0;
+    int frameNumber = m_currentFrameNumber - 1;
+    int frameCount = 0;
     double fpsVarianceNumerator = 0;
 
+    averageFPS = 0;
+    standardDeviation = 0;
+
     // Walk backwards through the samples looking for a run of good frame
     // timings from which to compute the mean and standard deviation.
     //
@@ -98,32 +101,29 @@ void FrameRateCounter::getAverageFPSAndStandardDeviation(double& averageFPS, dou
     // too much for short lived animations.
     //
     // isBadFrame encapsulates the frame too slow/frame too fast logic.
-    while (1) {
-        if (!isBadFrame(frame)) {
-            averageFPSCount++;
-            base::TimeDelta secForLastFrame = m_timeStampHistory[frameIndex(frame)] -
-                                              m_timeStampHistory[frameIndex(frame - 1)];
-            double x = 1.0 / secForLastFrame.InSecondsF();
+
+    // Go through all available historical data.
+    while (frameIndex(frameNumber) != frameIndex(m_currentFrameNumber) && frameNumber >= 0) {
+        base::TimeDelta delta = frameInterval(frameNumber);
+
+        if (!isBadFrameInterval(delta)) {
+            frameCount++;
+            double x = 1.0 / delta.InSecondsF();
             double deltaFromAverage = x - averageFPS;
             // Change with caution - numerics. http://en.wikipedia.org/wiki/Standard_deviation
-            averageFPS = averageFPS + deltaFromAverage / averageFPSCount;
-            fpsVarianceNumerator = fpsVarianceNumerator + deltaFromAverage * (x - averageFPS);
-        }
-        if (averageFPSCount && isBadFrame(frame)) {
+            averageFPS += deltaFromAverage / frameCount;
+            fpsVarianceNumerator += deltaFromAverage * (x - averageFPS);
+        } else if (frameCount)
             // We've gathered a run of good samples, so stop.
             break;
-        }
-        --frame;
-        if (frameIndex(frame) == frameIndex(m_currentFrameNumber) || frame < 0) {
-            // We've gone through all available historical data, so stop.
-            break;
-        }
+        frameNumber--;
     }
 
-    standardDeviation = sqrt(fpsVarianceNumerator / averageFPSCount);
+    if (frameCount)
+        standardDeviation = sqrt(fpsVarianceNumerator / frameCount);
 }
 
-base::TimeTicks FrameRateCounter::timeStampOfRecentFrame(int n)
+base::TimeTicks FrameRateCounter::timeStampOfRecentFrame(int n) const
 {
     DCHECK(n >= 0);
     DCHECK(n < kTimeStampHistorySize);
diff --git a/cc/frame_rate_counter.h b/cc/frame_rate_counter.h
index f9b770a..80697da 100644
--- a/cc/frame_rate_counter.h
+++ b/cc/frame_rate_counter.h
@@ -25,7 +25,8 @@ public:
 
     // n = 0 returns the oldest frame retained in the history,
     // while n = timeStampHistorySize() - 1 returns the timestamp most recent frame.
-    base::TimeTicks timeStampOfRecentFrame(int n);
+    // FIXME: Returns most recent timestamp for n = 0 when called between markBeginningOfFrame and markEndOfFrame calls.
+    base::TimeTicks timeStampOfRecentFrame(int n) const;
 
     // This is a heuristic that can be used to ignore frames in a reasonable way. Returns
     // true if the given frame interval is too fast or too slow, based on constant thresholds.
@@ -51,7 +52,7 @@ private:
     // FIXME: Determine this threshold based on monitor refresh rate, crbug.com/138642.
     static const double kDroppedFrameTime;
 
-    static const int kTimeStampHistorySize = 120;
+    static const int kTimeStampHistorySize = 170;
 
     int m_currentFrameNumber;
     base::TimeTicks m_timeStampHistory[kTimeStampHistorySize];
diff --git a/cc/heads_up_display_layer.cc b/cc/heads_up_display_layer.cc
index 0a9d47e..355c94d 100644
--- a/cc/heads_up_display_layer.cc
+++ b/cc/heads_up_display_layer.cc
@@ -21,7 +21,7 @@ HeadsUpDisplayLayer::HeadsUpDisplayLayer()
     : Layer()
 {
 
-    setBounds(gfx::Size(512, 128));
+    setBounds(gfx::Size(256, 128));
 }
 
 HeadsUpDisplayLayer::~HeadsUpDisplayLayer()
@@ -39,7 +39,7 @@ void HeadsUpDisplayLayer::update(ResourceUpdateQueue&, const OcclusionTracker*,
         int height = std::min(maxTextureSize, layerTreeHost()->deviceViewportSize().height());
         bounds = gfx::Size(width, height);
     } else {
-        bounds = gfx::Size(512, 128);
+        bounds = gfx::Size(256, 128);
     }
 
     setBounds(bounds);
diff --git a/cc/heads_up_display_layer_impl.cc b/cc/heads_up_display_layer_impl.cc
index a30cfc5..4444c9b 100644
--- a/cc/heads_up_display_layer_impl.cc
+++ b/cc/heads_up_display_layer_impl.cc
@@ -21,6 +21,7 @@
 #include "third_party/skia/include/core/SkPaint.h"
 #include "third_party/skia/include/effects/SkColorMatrixFilter.h"
 #include "ui/gfx/point.h"
+#include "ui/gfx/size.h"
 
 namespace cc {
 
@@ -43,6 +44,8 @@ static inline SkPaint createPaint()
 
 HeadsUpDisplayLayerImpl::HeadsUpDisplayLayerImpl(int id)
     : LayerImpl(id)
+    , m_averageFPS(0)
+    , m_stdDeviation(0)
 {
 }
 
@@ -143,17 +146,10 @@ void HeadsUpDisplayLayerImpl::drawHudContents(SkCanvas* canvas)
         canvas->drawRect(SkRect::MakeXYWH(0, 0, bounds().width(), bounds().height()), paint);
     }
 
-    int fpsCounterHeight = 40;
-    int fpsCounterTop = 2;
-    int platformLayerTreeTop;
+    int platformLayerTreeTop = 0;
 
     if (settings.showFPSCounter)
-        platformLayerTreeTop = fpsCounterTop + fpsCounterHeight;
-    else
-        platformLayerTreeTop = 0;
-
-    if (settings.showFPSCounter)
-        drawFPSCounter(canvas, layerTreeHostImpl()->fpsCounter(), fpsCounterTop, fpsCounterHeight);
+        platformLayerTreeTop = drawFPSCounter(canvas, layerTreeHostImpl()->fpsCounter());
 
     if (settings.showPlatformLayerTree && m_fontAtlas.get()) {
         std::string layerTree = layerTreeHostImpl()->layerTreeAsText();
@@ -164,77 +160,108 @@ void HeadsUpDisplayLayerImpl::drawHudContents(SkCanvas* canvas)
         drawDebugRects(canvas, layerTreeHostImpl()->debugRectHistory());
 }
 
-void HeadsUpDisplayLayerImpl::drawFPSCounter(SkCanvas* canvas, FrameRateCounter* fpsCounter, int top, int height)
+int HeadsUpDisplayLayerImpl::drawFPSCounter(SkCanvas* canvas, FrameRateCounter* fpsCounter)
 {
-    float textWidth = 170; // so text fits on linux.
-    float graphWidth = fpsCounter->timeStampHistorySize();
+    const int left = 2;
+    const int top = 2;
 
-    // Draw the FPS text.
-    drawFPSCounterText(canvas, fpsCounter, top, textWidth, height);
+    const int padding = 4;
 
-    // Draw FPS graph.
+    const int fontHeight = m_fontAtlas.get() ? m_fontAtlas->fontHeight() : 0;
+    const int graphWidth = fpsCounter->timeStampHistorySize() - 3;
+    const int graphHeight = 40;
+
+    const int width = graphWidth + 2 * padding;
+    const int height = fontHeight + graphHeight + 4 * padding + 2;
+
+    SkPaint paint = createPaint();
+
+    // Draw background.
+    paint.setColor(SkColorSetARGB(215, 17, 17, 17));
+    canvas->drawRect(SkRect::MakeXYWH(left, top, width, height), paint);
+
+    SkRect textBounds = SkRect::MakeXYWH(left + padding, top + padding, graphWidth, fontHeight);
+    SkRect graphBounds = SkRect::MakeXYWH(left + padding, textBounds.bottom() + 2 * padding, graphWidth, graphHeight);
+
+    drawFPSCounterText(canvas, paint, fpsCounter, textBounds);
+    drawFPSCounterGraph(canvas, paint, fpsCounter, graphBounds);
+
+    return top + height;
+}
+
+void HeadsUpDisplayLayerImpl::drawFPSCounterText(SkCanvas* canvas, SkPaint& paint, FrameRateCounter* fpsCounter, SkRect bounds)
+{
+    // Update FPS text - not every frame so text is readable
+    if (base::TimeDelta(fpsCounter->timeStampOfRecentFrame(0) - textUpdateTime).InSecondsF() > 0.25) {
+        fpsCounter->getAverageFPSAndStandardDeviation(m_averageFPS, m_stdDeviation);
+        textUpdateTime = fpsCounter->timeStampOfRecentFrame(0);
+    }
+
+    // Draw FPS text.
+    if (m_fontAtlas.get()) {
+        std::string fpsText = base::StringPrintf("FPS:%5.1f", m_averageFPS);
+        std::string deviationText = base::StringPrintf("+/-%4.1f", m_stdDeviation);
+
+        int deviationWidth = m_fontAtlas->textSize(deviationText).width();
+        gfx::Size textArea(bounds.width(), bounds.height());
+
+        paint.setColor(SK_ColorRED);
+        m_fontAtlas->drawText(canvas, paint, fpsText, gfx::Point(bounds.left(), bounds.top()), textArea);
+        m_fontAtlas->drawText(canvas, paint, deviationText, gfx::Point(bounds.right() - deviationWidth, bounds.top()), textArea);
+    }
+}
+
+void HeadsUpDisplayLayerImpl::drawFPSCounterGraph(SkCanvas* canvas, SkPaint& paint, FrameRateCounter* fpsCounter, SkRect bounds)
+{
     const double loFPS = 0;
     const double hiFPS = 80;
-    SkPaint paint = createPaint();
-    paint.setColor(SkColorSetRGB(154, 205, 50));
-    canvas->drawRect(SkRect::MakeXYWH(2 + textWidth, top, graphWidth, height / 2), paint);
 
-    paint.setColor(SkColorSetRGB(255, 250, 205));
-    canvas->drawRect(SkRect::MakeXYWH(2 + textWidth, top + height / 2, graphWidth, height / 2), paint);
+    paint.setStyle(SkPaint::kStroke_Style);
+    paint.setStrokeWidth(1);
+
+    // Draw top and bottom line.
+    paint.setColor(SkColorSetRGB(150, 150, 150));
+    canvas->drawLine(bounds.left(), bounds.top() - 1, bounds.right(), bounds.top() - 1, paint);
+    canvas->drawLine(bounds.left(), bounds.bottom(), bounds.right(), bounds.bottom(), paint);
 
-    int graphLeft = static_cast<int>(textWidth + 3);
+    // Draw 60fps line.
+    paint.setColor(SkColorSetRGB(100, 100, 100));
+    canvas->drawLine(bounds.left(), bounds.top() + bounds.height() / 4, bounds.right(), bounds.top() + bounds.height() / 4, paint);
+
+    // Draw FPS graph.
     int x = 0;
-    double h = static_cast<double>(height - 2);
     SkPath path;
-    for (int i = 0; i < fpsCounter->timeStampHistorySize() - 1; ++i) {
-        int j = i + 1;
-        base::TimeDelta delta = fpsCounter->timeStampOfRecentFrame(j) - fpsCounter->timeStampOfRecentFrame(i);
+
+    for (int i = 1; i < fpsCounter->timeStampHistorySize() - 1; ++i) {
+        base::TimeDelta delta = fpsCounter->timeStampOfRecentFrame(i + 1) - fpsCounter->timeStampOfRecentFrame(i);
 
         // Skip plotting this particular instantaneous frame rate if it is not likely to have been valid.
-        if (fpsCounter->isBadFrameInterval(delta)) {
-            x += 1;
-            continue;
+        if (!fpsCounter->isBadFrameInterval(delta)) {
+            double fps = 1.0 / delta.InSecondsF();
+
+            // Clamp the FPS to the range we want to plot visually.
+            double p = 1 - ((fps - loFPS) / (hiFPS - loFPS));
+            if (p < 0)
+                p = 0;
+            if (p > 1)
+                p = 1;
+
+            // Plot this data point.
+            SkPoint cur = SkPoint::Make(bounds.left() + x, bounds.top() + p * bounds.height());
+            if (path.isEmpty())
+                path.moveTo(cur);
+            else
+                path.lineTo(cur);
         }
 
-        double fps = 1.0 / delta.InSecondsF();
-
-        // Clamp the FPS to the range we want to plot visually.
-        double p = 1 - ((fps - loFPS) / (hiFPS - loFPS));
-        if (p < 0)
-            p = 0;
-        if (p > 1)
-            p = 1;
-
-        // Plot this data point.
-        SkPoint cur = SkPoint::Make(graphLeft + x, 1 + top + p*h);
-        if (path.isEmpty())
-            path.moveTo(cur);
-        else
-            path.lineTo(cur);
         x += 1;
     }
-    paint.setColor(SK_ColorRED);
-    paint.setStyle(SkPaint::kStroke_Style);
-    paint.setStrokeWidth(1);
+
     paint.setAntiAlias(true);
+    paint.setColor(SK_ColorRED);
     canvas->drawPath(path, paint);
 }
 
-void HeadsUpDisplayLayerImpl::drawFPSCounterText(SkCanvas* canvas, FrameRateCounter* fpsCounter, int top, int width, int height)
-{
-    double averageFPS, stdDeviation;
-    fpsCounter->getAverageFPSAndStandardDeviation(averageFPS, stdDeviation);
-
-    // Draw background.
-    SkPaint paint = createPaint();
-    paint.setColor(SK_ColorBLACK);
-    canvas->drawRect(SkRect::MakeXYWH(2, top, width, height), paint);
-
-    // Draw FPS text.
-    if (m_fontAtlas.get())
-        m_fontAtlas->drawText(canvas, createPaint(), base::StringPrintf("FPS: %4.1f +/- %3.1f", averageFPS, stdDeviation), gfx::Point(10, height / 3), gfx::Size(width, height));
-}
-
 void HeadsUpDisplayLayerImpl::drawDebugRects(SkCanvas* canvas, DebugRectHistory* debugRectHistory)
 {
     const std::vector<DebugRect>& debugRects = debugRectHistory->debugRects();
diff --git a/cc/heads_up_display_layer_impl.h b/cc/heads_up_display_layer_impl.h
index bcca767..3276293 100644
--- a/cc/heads_up_display_layer_impl.h
+++ b/cc/heads_up_display_layer_impl.h
@@ -6,12 +6,15 @@
 #define CC_HEADS_UP_DISPLAY_LAYER_IMPL_H_
 
 #include "base/memory/scoped_ptr.h"
+#include "base/time.h"
 #include "cc/cc_export.h"
 #include "cc/font_atlas.h"
 #include "cc/layer_impl.h"
 #include "cc/scoped_texture.h"
 
 class SkCanvas;
+class SkPaint;
+struct SkRect;
 
 namespace cc {
 
@@ -44,13 +47,19 @@ private:
     virtual const char* layerTypeAsString() const OVERRIDE;
 
     void drawHudContents(SkCanvas*);
-    void drawFPSCounter(SkCanvas*, FrameRateCounter*, int top, int height);
-    void drawFPSCounterText(SkCanvas*, FrameRateCounter*, int top, int width, int height);
+    int drawFPSCounter(SkCanvas*, FrameRateCounter*);
+    void drawFPSCounterText(SkCanvas*, SkPaint&, FrameRateCounter*, SkRect);
+    void drawFPSCounterGraph(SkCanvas*, SkPaint&, FrameRateCounter*, SkRect);
     void drawDebugRects(SkCanvas*, DebugRectHistory*);
 
     scoped_ptr<FontAtlas> m_fontAtlas;
     scoped_ptr<ScopedTexture> m_hudTexture;
     scoped_ptr<SkCanvas> m_hudCanvas;
+
+    double m_averageFPS;
+    double m_stdDeviation;
+
+    base::TimeTicks textUpdateTime;
 };
 
 }  // namespace cc