Clarify the default algorithm used to choose an EGLConfig. (83835359) · Commits · e / os / android_frameworks_base

opengl/java/android/opengl/GLSurfaceView.java

+39 −35

Original line number	Diff line number	Diff line
		@@ -30,6 +30,7 @@ import javax.microedition.khronos.opengles.GL10;

		import android.content.Context;
		import android.content.pm.ConfigurationInfo;
		import android.graphics.PixelFormat;
		import android.os.SystemProperties;
		import android.util.AttributeSet;
		import android.util.Log;
		@@ -75,15 +76,23 @@ import android.view.SurfaceView;
		* <li>{@link #setGLWrapper(GLWrapper)}
		* </ul>
		* <p>
		* <h4>Specifying the android.view.Surface</h4>
		* By default GLSurfaceView will create a PixelFormat.RGB_565 format surface. If a translucent
		* surface is required, call getHolder().setFormat(PixelFormat.TRANSLUCENT).
		* The exact format of a TRANSLUCENT surface is device dependent, but it will be
		* a 32-bit-per-pixel surface with 8 bits per component.
		* <p>
		* <h4>Choosing an EGL Configuration</h4>
		* A given Android device may support multiple possible types of drawing surfaces.
		* The available surfaces may differ in how may channels of data are present, as
		* A given Android device may support multiple EGLConfig rendering configurations.
		* The available configurations may differ in how may channels of data are present, as
		* well as how many bits are allocated to each channel. Therefore, the first thing
		* GLSurfaceView has to do when starting to render is choose what type of surface to use.
		* GLSurfaceView has to do when starting to render is choose what EGLConfig to use.
		* <p>
		* By default GLSurfaceView chooses a EGLConfig that has an RGB_656 pixel format,
		* with at least a 16-bit depth buffer and no stencil.
		* <p>
		* By default GLSurfaceView chooses an available surface that's closest to a 16-bit R5G6B5 surface
		* with a 16-bit depth buffer and no stencil. If you would prefer a different surface (for example,
		* if you do not need a depth buffer) you can override the default behavior by calling one of the
		* If you would prefer a different EGLConfig
		* you can override the default behavior by calling one of the
		* setEGLConfigChooser methods.
		* <p>
		* <h4>Debug Behavior</h4>
		@@ -211,6 +220,7 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
		// underlying surface is created and destroyed
		SurfaceHolder holder = getHolder();
		holder.addCallback(this);
		holder.setFormat(PixelFormat.RGB_565);
		// setType is not needed for SDK 2.0 or newer. Uncomment this
		// statement if back-porting this code to older SDKs.
		// holder.setType(SurfaceHolder.SURFACE_TYPE_GPU);
		@@ -331,8 +341,9 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
		* is called.
		* <p>
		* If no setEGLConfigChooser method is called, then by default the
		* view will choose a config as close to 16-bit RGB as possible, with
		* a depth buffer as close to 16 bits as possible.
		* view will choose an EGLConfig that is compatible with the current
		* android.view.Surface, with a depth buffer depth of
		* at least 16 bits.
		* @param configChooser
		*/
		public void setEGLConfigChooser(EGLConfigChooser configChooser) {
		@@ -349,8 +360,8 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
		* is called.
		* <p>
		* If no setEGLConfigChooser method is called, then by default the
		* view will choose a config as close to 16-bit RGB as possible, with
		* a depth buffer as close to 16 bits as possible.
		* view will choose an RGB_565 surface with a depth buffer depth of
		* at least 16 bits.
		*
		* @param needDepth
		*/
		@@ -360,15 +371,15 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback

		/**
		* Install a config chooser which will choose a config
		* with at least the specified component sizes, and as close
		* to the specified component sizes as possible.
		* with at least the specified depthSize and stencilSize,
		* and exactly the specified redSize, greenSize, blueSize and alphaSize.
		* <p>If this method is
		* called, it must be called before {@link #setRenderer(Renderer)}
		* is called.
		* <p>
		* If no setEGLConfigChooser method is called, then by default the
		* view will choose a config as close to 16-bit RGB as possible, with
		* a depth buffer as close to 16 bits as possible.
		* view will choose an RGB_565 surface with a depth buffer depth of
		* at least 16 bits.
		*
		*/
		public void setEGLConfigChooser(int redSize, int greenSize, int blueSize,
		@@ -775,6 +786,10 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
		}
		}

		/**
		* Choose a configuration with exactly the specified r,g,b,a sizes,
		* and at least the specified depth and stencil sizes.
		*/
		private class ComponentSizeChooser extends BaseConfigChooser {
		public ComponentSizeChooser(int redSize, int greenSize, int blueSize,
		int alphaSize, int depthSize, int stencilSize) {
		@@ -798,14 +813,12 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
		@Override
		public EGLConfig chooseConfig(EGL10 egl, EGLDisplay display,
		EGLConfig[] configs) {
		EGLConfig closestConfig = null;
		int closestDistance = 1000;
		for (EGLConfig config : configs) {
		int d = findConfigAttrib(egl, display, config,
		EGL10.EGL_DEPTH_SIZE, 0);
		int s = findConfigAttrib(egl, display, config,
		EGL10.EGL_STENCIL_SIZE, 0);
		if (d >= mDepthSize && s>= mStencilSize) {
		if ((d >= mDepthSize) && (s >= mStencilSize)) {
		int r = findConfigAttrib(egl, display, config,
		EGL10.EGL_RED_SIZE, 0);
		int g = findConfigAttrib(egl, display, config,
		@@ -814,17 +827,13 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
		EGL10.EGL_BLUE_SIZE, 0);
		int a = findConfigAttrib(egl, display, config,
		EGL10.EGL_ALPHA_SIZE, 0);
		int distance = Math.abs(r - mRedSize)
		+ Math.abs(g - mGreenSize)
		+ Math.abs(b - mBlueSize)
		+ Math.abs(a - mAlphaSize);
		if (distance < closestDistance) {
		closestDistance = distance;
		closestConfig = config;
		if ((r == mRedSize) && (g == mGreenSize)
		&& (b == mBlueSize) && (a == mAlphaSize)) {
		return config;
		}
		}
		}
		return closestConfig;
		return null;
		}

		private int findConfigAttrib(EGL10 egl, EGLDisplay display,
		@@ -847,18 +856,13 @@ public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback
		}

		/**
		* This class will choose a supported surface as close to
		* RGB565 as possible, with or without a depth buffer.
		* This class will choose a RGB_565 surface with
		* or without a depth buffer.
		*
		*/
		private class SimpleEGLConfigChooser extends ComponentSizeChooser {
		public SimpleEGLConfigChooser(boolean withDepthBuffer) {
		super(4, 4, 4, 0, withDepthBuffer ? 16 : 0, 0);
		// Adjust target values. This way we'll accept a 4444 or
		// 555 buffer if there's no 565 buffer available.
		mRedSize = 5;
		mGreenSize = 6;
		mBlueSize = 5;
		super(5, 6, 5, 0, withDepthBuffer ? 16 : 0, 0);
		}
		}