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Show a warning if the image has an empty alpha channel.
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If the image has an alpha channel, where all values are below a threshold,
a warning and option to disable the alpha channel are shown. If the alpha
channel is disabled through this option and later an image with an alpha
channel is selected, a warning and option to re-enable the alpha channel
are shown.

Fixes #723
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@pmuetschard
pmuetschard committed Oct 12, 2017
1 parent 0dad9d0 commit 944094d
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Showing 4 changed files with 184 additions and 9 deletions.
76 changes: 72 additions & 4 deletions gapic/src/main/com/google/gapid/image/ArrayImage.java
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
import static com.google.gapid.util.Colors.DARK_LUMINANCE_THRESHOLD;
import static com.google.gapid.util.Colors.clamp;

import com.google.common.primitives.UnsignedBytes;
import com.google.gapid.glviewer.gl.Texture;
import com.google.gapid.util.Colors;

Expand Down Expand Up @@ -168,8 +169,11 @@ public Builder flip() {
* An {@link ArrayImage} that represents an RGBA image with 8bit color channels.
*/
public static class RGBA8Image extends ArrayImage {
private final PixelInfo info;

public RGBA8Image(int width, int height, int depth, byte[] data) {
super(width, height, depth, 4, data, GL11.GL_RGBA8, GL11.GL_RGBA, GL11.GL_UNSIGNED_BYTE);
this.info = IntPixelInfo.compute(data);
}

@Override
Expand Down Expand Up @@ -202,7 +206,7 @@ protected PixelValue getPixel(int x, int y, byte[] data) {

@Override
public PixelInfo getInfo() {
return PixelInfo.NULL_INFO;
return info;
}

private static class Pixel implements PixelValue {
Expand Down Expand Up @@ -420,10 +424,13 @@ public boolean isDark() {

private static class FloatPixelInfo implements PixelInfo {
private final float min, max;
private final float alphaMin, alphaMax;

private FloatPixelInfo(float min, float max) {
private FloatPixelInfo(float min, float max, float alphaMin, float alphaMax) {
this.min = min;
this.max = max;
this.alphaMin = alphaMin;
this.alphaMax = alphaMax;
}

public static PixelInfo compute(FloatBuffer buffer, boolean isRGBA) {
Expand All @@ -432,7 +439,10 @@ public static PixelInfo compute(FloatBuffer buffer, boolean isRGBA) {
}

float min = Float.POSITIVE_INFINITY, max = Float.NEGATIVE_INFINITY;
float alphaMin, alphaMax;
if (isRGBA) {
alphaMin = Float.POSITIVE_INFINITY;
alphaMax = Float.NEGATIVE_INFINITY;
for (int i = 0, end = buffer.remaining() - 3; i <= end; ) {
float value = buffer.get(i++);
if (!Float.isNaN(value) && !Float.isInfinite(value)) {
Expand All @@ -449,9 +459,14 @@ public static PixelInfo compute(FloatBuffer buffer, boolean isRGBA) {
min = Math.min(min, value);
max = Math.max(max, value);
}
i++; // skip alpha
value = buffer.get(i++);
if (!Float.isNaN(value) && !Float.isInfinite(value)) {
alphaMin = Math.min(alphaMin, value);
alphaMax = Math.max(alphaMax, value);
}
}
} else {
alphaMin = alphaMax = 1;
for (int i = 0; i < buffer.remaining(); i++) {
float value = buffer.get(i);
if (!Float.isNaN(value) && !Float.isInfinite(value)) {
Expand All @@ -460,7 +475,7 @@ public static PixelInfo compute(FloatBuffer buffer, boolean isRGBA) {
}
}
}
return new FloatPixelInfo(min, max);
return new FloatPixelInfo(min, max, alphaMin, alphaMax);
}

@Override
Expand All @@ -472,5 +487,58 @@ public float getMin() {
public float getMax() {
return max;
}

@Override
public float getAlphaMin() {
return alphaMin;
}

@Override
public float getAlphaMax() {
return alphaMax;
}
}

private static class IntPixelInfo implements PixelInfo {
private final float alphaMin, alphaMax;

private IntPixelInfo(float alphaMin, float alphaMax) {
this.alphaMin = alphaMin;
this.alphaMax = alphaMax;
}

public static PixelInfo compute(byte[] rgba) {
if (rgba.length == 0) {
return PixelInfo.NULL_INFO;
}

int alphaMin = Integer.MAX_VALUE, alphaMax = Integer.MIN_VALUE;
for (int i = 3; i < rgba.length; i += 4) {
int value = UnsignedBytes.toInt(rgba[i]);
alphaMin = Math.min(alphaMin, value);
alphaMax = Math.max(alphaMax, value);
}
return new IntPixelInfo(alphaMin / 255f, alphaMax / 255f);
}

@Override
public float getMin() {
return 0; // Disable automatic tone-mapping.
}

@Override
public float getMax() {
return 1; // Disable automatic tone-mapping.
}

@Override
public float getAlphaMin() {
return alphaMin;
}

@Override
public float getAlphaMax() {
return alphaMax;
}
}
}
20 changes: 20 additions & 0 deletions gapic/src/main/com/google/gapid/image/Image.java
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Original file line number Diff line number Diff line change
Expand Up @@ -153,6 +153,16 @@ public float getMin() {
public float getMax() {
return 1;
}

@Override
public float getAlphaMin() {
return 1;
}

@Override
public float getAlphaMax() {
return 1;
}
};

/**
Expand All @@ -164,5 +174,15 @@ public float getMax() {
* @return the maximum value across all channels of the image data. Used for tone mapping.
*/
public float getMax();

/**
* @return the minimum alpha value of the image data.
*/
public float getAlphaMin();

/**
* @return the maximum alpha value of the image data.
*/
public float getAlphaMax();
}
}
96 changes: 91 additions & 5 deletions gapic/src/main/com/google/gapid/widgets/ImagePanel.java
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
import static com.google.gapid.widgets.Widgets.createSeparator;
import static com.google.gapid.widgets.Widgets.createToggleToolItem;
import static com.google.gapid.widgets.Widgets.createToolItem;
import static com.google.gapid.widgets.Widgets.withSpans;

import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
Expand Down Expand Up @@ -84,6 +85,7 @@
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ExecutionException;
import java.util.function.Consumer;
import java.util.function.IntConsumer;
import java.util.logging.Logger;

Expand All @@ -94,6 +96,7 @@ public class ImagePanel extends Composite {
protected static final Logger LOG = Logger.getLogger(ImagePanel.class.getName());
protected static final int ZOOM_AMOUNT = 5;
private static final int CHANNEL_RED = 0, CHANNEL_GREEN = 1, CHANNEL_BLUE = 2, CHANNEL_ALPHA = 3;
private static final float ALPHA_WARNING_THRESHOLD = 2 / 255f;
private static final Image[] NO_LAYERS = new Image[] { Image.EMPTY };

private final SingleInFlight imageRequestController = new SingleInFlight();
Expand All @@ -112,8 +115,8 @@ public ImagePanel(Composite parent, Widgets widgets, boolean naturallyFlipped) {
setLayout(Widgets.withMargin(new GridLayout(1, false), 5, 2));

loading = LoadablePanel.create(this, widgets, panel ->
new ImageComponent(panel, widgets.theme, naturallyFlipped));
status = new StatusBar(this, this::loadLevel);
new ImageComponent(panel, widgets.theme, this::showAlphaWarning, naturallyFlipped));
status = new StatusBar(this, widgets.theme, this::loadLevel, this::setAlphaEnabled);
imageComponent = loading.getContents();

loading.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
Expand Down Expand Up @@ -185,6 +188,14 @@ protected void setPreviewPixel(Pixel pixel) {
status.setPixel(pixel);
}

private void showAlphaWarning(AlphaWarning message) {
status.showAlphaWarning(message);
}

private void setAlphaEnabled(boolean enabled) {
imageComponent.autoToggleAlphaChannel(enabled);
}

public void createToolbar(ToolBar bar, Theme theme) {
zoomFitItem = createToggleToolItem(bar, theme.zoomFit(),
e -> setZoomToFit(((ToolItem)e.widget).getSelection()), "Zoom to fit");
Expand Down Expand Up @@ -400,6 +411,7 @@ private static class ImageComponent extends Composite {
private static final double MAX_ZOOM_FACTOR = 8;
private static final VecD MIN_ZOOM_SIZE = new VecD(100, 100, 0);

private final Consumer<AlphaWarning> showAlphaWarning;
private final boolean naturallyFlipped;

private final ScrollBar scrollbars[];
Expand All @@ -422,10 +434,14 @@ private static class ImageComponent extends Composite {
private double scaleGridToView = 1.0;
private boolean zoomToFit;

public ImageComponent(Composite parent, Theme theme, boolean naturallyFlipped) {
private boolean alphaWasAutoDisabled = false;

public ImageComponent(Composite parent, Theme theme, Consumer<AlphaWarning> showAlphaWarning,
boolean naturallyFlipped) {
super(parent, SWT.BORDER | SWT.V_SCROLL | SWT.H_SCROLL | SWT.NO_BACKGROUND);
setLayout(new FillLayout(SWT.VERTICAL));

this.showAlphaWarning = showAlphaWarning;
this.naturallyFlipped = naturallyFlipped;

scrollbars = new ScrollBar[] { getHorizontalBar(), getVerticalBar() };
Expand Down Expand Up @@ -492,6 +508,33 @@ private void refresh() {
data.images = images;
data.transforms = calcTransforms();
canvas.setSceneData(data.copy());

if (images.length == 0) {
showAlphaWarning.accept(AlphaWarning.NONE);
} else if (isChannelEnabled(CHANNEL_ALPHA)) {
boolean noAlpha = true;
for (Image image : images) {
if (image.getInfo().getAlphaMax() > ALPHA_WARNING_THRESHOLD) {
noAlpha = false;
break;
}
}
showAlphaWarning.accept(noAlpha ? AlphaWarning.NO_ALPHA : AlphaWarning.NONE);
} else if (alphaWasAutoDisabled) {
boolean noAlpha = true;
for (Image image : images) {
PixelInfo info = image.getInfo();
if (info.getAlphaMax() > ALPHA_WARNING_THRESHOLD &&
info.getAlphaMin() < 1 - ALPHA_WARNING_THRESHOLD) {
// Consider an image with all alpha values mostly 1.0 as an image without alpha.
noAlpha = false;
break;
}
}
showAlphaWarning.accept(noAlpha ? AlphaWarning.NONE : AlphaWarning.ALPHA_DISABLED);
} else {
showAlphaWarning.accept(AlphaWarning.NONE);
}
}

public void setPreviewPixel(Pixel previewPixel) {
Expand Down Expand Up @@ -524,6 +567,15 @@ protected boolean isChannelEnabled(int channel) {

protected void setChannelEnabled(int channel, boolean enabled) {
data.channels[channel] = enabled;
if (channel == CHANNEL_ALPHA) {
alphaWasAutoDisabled = false;
}
refresh();
}

protected void autoToggleAlphaChannel(boolean enabled) {
alphaWasAutoDisabled = true;
data.channels[CHANNEL_ALPHA] = enabled;
refresh();
}

Expand Down Expand Up @@ -709,7 +761,6 @@ private static class ImageScene implements Scene<SceneData> {
private static final int PREVIEW_HEIGHT = 11; // Should be odd, so center pixel looks nice.
private static final int PREVIEW_SIZE = 7;


private final Map<Image, Texture> imageToTexture = Maps.newHashMap();
private Shader shader;
private Texture[] textures;
Expand Down Expand Up @@ -964,9 +1015,12 @@ private static class StatusBar extends Composite {
private final Label levelValue;
private final Label levelSize;
private final Label pixelLabel;
private final Label warning;
private int lastSelection = 0;
private AlphaWarning lastWarning = AlphaWarning.NONE;

public StatusBar(Composite parent, IntConsumer levelListener) {
public StatusBar(
Composite parent, Theme theme, IntConsumer levelListener, Consumer<Boolean> enableAlpha) {
super(parent, SWT.NONE);
setLayout(new GridLayout(3, false));

Expand All @@ -976,10 +1030,15 @@ public StatusBar(Composite parent, IntConsumer levelListener) {
levelScale = createScale(levelComposite);
levelSize = createLabel(this, "");
pixelLabel = createLabel(this, "");
warning = createLabel(this, "");
warning.setForeground(theme.imageWarning());
warning.setCursor(getDisplay().getSystemCursor(SWT.CURSOR_HAND));

levelComposite.setLayoutData(new GridData(SWT.LEFT, SWT.CENTER, false, true));
levelSize.setLayoutData(new GridData(SWT.LEFT, SWT.CENTER, false, true));
pixelLabel.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, true));
warning.setLayoutData(withSpans(new GridData(SWT.CENTER, SWT.CENTER, true, false), 3, 1));
showAlphaWarning(AlphaWarning.NONE);

levelScale.addListener(SWT.Selection, e -> {
int selection = levelScale.getSelection();
Expand All @@ -990,6 +1049,9 @@ public StatusBar(Composite parent, IntConsumer levelListener) {
levelListener.accept(selection);
}
});
warning.addListener(SWT.MouseUp,
e -> enableAlpha.accept(lastWarning == AlphaWarning.ALPHA_DISABLED));

setLevelCount(0);
}

Expand Down Expand Up @@ -1019,6 +1081,18 @@ public void setPixel(Pixel pixel) {
requestLayout();
}

public void showAlphaWarning(AlphaWarning message) {
if (lastWarning == message) {
return;
}

lastWarning = message;
((GridData)warning.getLayoutData()).exclude = message == AlphaWarning.NONE;
warning.setVisible(message != AlphaWarning.NONE);
warning.setText(message.warning);
requestLayout();
}

private static Scale createScale(Composite parent) {
Scale scale = new Scale(parent, SWT.HORIZONTAL);
scale.setMinimum(0);
Expand All @@ -1029,4 +1103,16 @@ private static Scale createScale(Composite parent) {
return scale;
}
}

private static enum AlphaWarning {
NONE(""),
NO_ALPHA("The alpha channels appears to be empty. Click to disable the alpha channel."),
ALPHA_DISABLED("Image contains an alpha channel. Click to re-enable alpha channel.");

public final String warning;

private AlphaWarning(String warning) {
this.warning = warning;
}
}
}
1 change: 1 addition & 0 deletions gapic/src/main/com/google/gapid/widgets/Theme.java
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Original file line number Diff line number Diff line change
Expand Up @@ -138,6 +138,7 @@ public interface Theme {
@RGB(argb = 0xffffffff) public Color imageCheckerLight();
@RGB(argb = 0xff000000) public Color imageCursorDark();
@RGB(argb = 0xffffffff) public Color imageCursorLight();
@RGB(argb = 0xffff9900) public Color imageWarning();

@TextStyle(foreground = 0xa9a9a9) public Styler structureStyler();
@TextStyle(foreground = 0x0000ee) public Styler identifierStyler();
Expand Down

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