Android: Add helper class GlTextureFrameBuffer

talk/app/webrtc/java/android/org/webrtc/GlTextureFrameBuffer.java

Index: talk/app/webrtc/java/android/org/webrtc/GlTextureFrameBuffer.java
diff --git a/talk/app/webrtc/java/android/org/webrtc/GlTextureFrameBuffer.java b/talk/app/webrtc/java/android/org/webrtc/GlTextureFrameBuffer.java
new file mode 100644
index 0000000000000000000000000000000000000000..fd52c37eb4c085ae374ece167cf26e921b57b032
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+++ b/talk/app/webrtc/java/android/org/webrtc/GlTextureFrameBuffer.java
@@ -0,0 +1,142 @@
+/*
+ * libjingle
+ * Copyright 2015 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  1. Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright notice,
+ *     this list of conditions and the following disclaimer in the documentation
+ *     and/or other materials provided with the distribution.
+ *  3. The name of the author may not be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+ * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.webrtc;
+
+import android.opengl.GLES20;
+
+/**
+ * Helper class for handling OpenGL framebuffer with only color attachment and no depth or stencil
+ * buffer. Intended for simple tasks such as texture copy, texture downscaling, and texture color
+ * conversion.
+ */
+// TODO(magjed): Add unittests for this class.

[hbos, 2015/09/18 11:27:35]

Would be nice, yes. Doesn't have to be in this CL.

+public class GlTextureFrameBuffer {
+  private final int frameBufferId;
+  private final int textureId;
+  private final int pixelFormat;
+  private int width;
+  private int height;
+
+  /**
+   * Generate texture and framebuffer resources. An EGLContext must be bound on the current thread

[hbos, 2015/09/18 11:27:35]

Here and other methods assuming its not expensive: is there a way to check if an
EGLContext has been bound and throw an exception otherwise?

[magjed_webrtc, 2015/09/18 14:32:03]

Hmm, yes maybe. But when this happens, an exception is thrown anyway with a good
error message, something like "No EGLContext bound". Might be good anyway to
make it explicit and obvious, but will not add in this CL.

+   * when calling this function. The framebuffer is not complete until setSize() is called.
+   */
+  public GlTextureFrameBuffer(int pixelFormat) {
+    switch (pixelFormat) {
+      case GLES20.GL_LUMINANCE:
+      case GLES20.GL_RGB:
+      case GLES20.GL_RGBA:
+        this.pixelFormat = pixelFormat;
+        break;
+      default:
+        throw new IllegalArgumentException("Invalid pixel format: " + pixelFormat);
+    }
+
+    textureId = GlUtil.generateTexture(GLES20.GL_TEXTURE_2D);
+    this.width = 0;
+    this.height = 0;
+
+    // Create framebuffer object and bind it.
+    final int frameBuffers[] = new int[1];
+    GLES20.glGenFramebuffers(1, frameBuffers, 0);
+    frameBufferId = frameBuffers[0];
+    GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, frameBufferId);
+    GlUtil.checkNoGLES2Error("Generate framebuffer");
+
+    // Attach the texture to the framebuffer as color attachment.
+    GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER, GLES20.GL_COLOR_ATTACHMENT0,
+        GLES20.GL_TEXTURE_2D, textureId, 0);
+    GlUtil.checkNoGLES2Error("Attach texture to framebuffer");
+
+    // Restore normal framebuffer.
+    GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);
+  }
+
+  /**
+   * (Re)allocate texture. Will do nothing if the requested size equals the current size. An
+   * EGLContext must be bound on the current thread when calling this function. Must be called at
+   * least once before using the framebuffer. May be called multiple times to change size.
+   */
+  public void setSize(int width, int height) {
+    if (width == 0 || height == 0) {
+      throw new IllegalArgumentException("Invalid size: " + width + "x" + height);
+    }
+    if (width == this.width && height == this.height) {
+      return;
+    }
+    this.width = width;
+    this.height = height;
+
+    // Bind our framebuffer.
+    GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, frameBufferId);
+    GlUtil.checkNoGLES2Error("glBindFramebuffer");
+
+    // Allocate texture.
+    GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
+    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);
+    GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, pixelFormat, width, height, 0, pixelFormat,
+        GLES20.GL_UNSIGNED_BYTE, null);
+
+    // Check that the framebuffer is in a good state.
+    final int status = GLES20.glCheckFramebufferStatus(GLES20.GL_FRAMEBUFFER);
+    if (status != GLES20.GL_FRAMEBUFFER_COMPLETE) {
+      throw new IllegalStateException("Framebuffer not complete, status: " + status);
+    }
+
+    // Restore normal framebuffer.
+    GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);
+    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
+  }
+
+  public int getWidth() {
+    return width;
+  }
+
+  public int getHeight() {
+    return height;
+  }
+
+  public int getFrameBufferId() {
+    return frameBufferId;
+  }
+
+  public int getTextureId() {
+    return textureId;
+  }
+
+  /**
+   * Release texture and framebuffer. An EGLContext must be bound on the current thread when calling
+   * this function. This object should not be used after this call.
+   */
+  public void release() {
+    GLES20.glDeleteTextures(1, new int[] {textureId}, 0);
+    GLES20.glDeleteFramebuffers(1, new int[] {frameBufferId}, 0);
+    width = 0;
+    height = 0;
+  }
+}