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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package com.sun.glass.ui.monocle;
import com.sun.javafx.logging.PlatformLogger;
import com.sun.javafx.util.Logging;
import java.io.IOException;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.IntBuffer;
import java.nio.ShortBuffer;
import java.nio.channels.WritableByteChannel;
import java.text.MessageFormat;
/**
* Provides a buffer for composing JavaFX scenes. This class is given a 32-bit
* composition buffer that is either the Linux frame buffer itself or an
* off-screen byte buffer. It can write the contents of this buffer to a target
* channel, or copy them to a buffer, in one of three pixel formats: 32-bit
* ARGB32 color, 16-bit RGB565 color, or 8-bit Y8 grayscale.
*/
class FramebufferY8 extends Framebuffer {
/**
* The arithmetic right shift value to convert a bit depth to a byte depth.
*/
private static final int BITS_TO_BYTES = 3;
private final PlatformLogger logger = Logging.getJavaFXLogger();
private final ByteBuffer bb;
private final int width;
private final int height;
private final int bitDepth;
private final int byteDepth;
private ByteBuffer lineByteBuffer;
private Buffer linePixelBuffer;
/**
* Creates a new {@code FramebufferY8} with the given 32-bit composition
* buffer and target color depth.
*
* @param bb the 32-bit composition buffer
* @param width the width of the composition buffer in pixels
* @param height the height of the composition buffer in pixels
* @param depth the color depth of the target channel or buffer in bits per
* pixel
* @param clear {@code true} to clear the composition buffer on the first
* upload of each frame unless that upload already overwrites the entire
* buffer; otherwise {@code false}
*/
FramebufferY8(ByteBuffer bb, int width, int height, int depth, boolean clear) {
super(bb, width, height, depth, clear);
this.bb = bb;
this.width = width;
this.height = height;
this.bitDepth = depth;
this.byteDepth = depth >>> BITS_TO_BYTES;
if (byteDepth != Integer.BYTES && byteDepth != Short.BYTES && byteDepth != Byte.BYTES) {
String msg = MessageFormat.format("Unsupported color depth: {0} bpp", bitDepth);
logger.severe(msg);
throw new IllegalArgumentException(msg);
}
}
/**
* Copies the next 32-bit ARGB32 pixel to a byte buffer with 8-bit Y8
* pixels. Luma Y' can be calculated from gamma-corrected R'G'B' using the
* following coefficients. This method uses the coefficients from Rec. 709,
* which defines the same primaries and white point as the sRGB color space.
* {@code
* Simple average: Y' = (R' + G' + B') / 3
* Rec. 601 (SDTV): Y' = 0.299 * R' + 0.587 * G' + 0.114 * B'
* Rec. 709 (HDTV): Y' = 0.2126 * R' + 0.7152 * G' + 0.0722 * B'
* Rec. 2100 (HDR): Y' = 0.2627 * R' + 0.6780 * G' + 0.0593 * B'
* }
*
* @implNote Java rounds toward zero when converting a {@code float} to an
* {@code int}. The calculation of luma could be rounded to the nearest
* integer by adding 0.5 before the type conversion, but the extra operation
* seems unnecessary for a display with only 16 levels of gray.
*
* @param source the source integer buffer in ARGB32 format
* @param target the target byte buffer in Y8 format
*/
private void copyNextPixel(IntBuffer source, ByteBuffer target) {
int pixel32 = source.get();
int r = (pixel32 >> 16) & 0xFF;
int g = (pixel32 >> 8) & 0xFF;
int b = pixel32 & 0xFF;
int y = (int) (0.2126f * r + 0.7152f * g + 0.0722f * b);
target.put((byte) y);
}
/**
* Copies the next 32-bit ARGB32 pixel to a short buffer with 16-bit RGB565
* pixels. This method truncates the low-order bits of each color component.
*
* @param source the source integer buffer in ARGB32 format
* @param target the target short buffer in RGB565 format
*/
private void copyNextPixel(IntBuffer source, ShortBuffer target) {
int pixel32 = source.get();
int r = (pixel32 >> 8) & 0xF800;
int g = (pixel32 >> 5) & 0x07E0;
int b = (pixel32 >> 3) & 0x001F;
int pixel16 = r | g | b;
target.put((short) pixel16);
}
/**
* Writes the contents of the composition buffer to the output channel,
* converting the pixel format as necessary.
*
* @param out the output channel
* @throws IOException if an error occurs writing to the channel
* @throws IllegalArgumentException if the channel has an unsupported color
* depth
*/
@Override
void write(WritableByteChannel out) throws IOException {
bb.clear();
switch (byteDepth) {
case Byte.BYTES: {
if (lineByteBuffer == null) {
lineByteBuffer = ByteBuffer.allocate(width * Byte.BYTES);
lineByteBuffer.order(ByteOrder.nativeOrder());
linePixelBuffer = lineByteBuffer.duplicate();
}
IntBuffer srcPixels = bb.asIntBuffer();
ByteBuffer byteBuffer = (ByteBuffer) linePixelBuffer;
for (int y = 0; y < height; y++) {
byteBuffer.clear();
for (int x = 0; x < width; x++) {
copyNextPixel(srcPixels, byteBuffer);
}
lineByteBuffer.clear();
out.write(lineByteBuffer);
}
break;
}
case Short.BYTES: {
if (lineByteBuffer == null) {
lineByteBuffer = ByteBuffer.allocate(width * Short.BYTES);
lineByteBuffer.order(ByteOrder.nativeOrder());
linePixelBuffer = lineByteBuffer.asShortBuffer();
}
IntBuffer srcPixels = bb.asIntBuffer();
ShortBuffer shortBuffer = (ShortBuffer) linePixelBuffer;
for (int y = 0; y < height; y++) {
shortBuffer.clear();
for (int x = 0; x < width; x++) {
copyNextPixel(srcPixels, shortBuffer);
}
lineByteBuffer.clear();
out.write(lineByteBuffer);
}
break;
}
case Integer.BYTES: {
out.write(bb);
break;
}
default:
String msg = MessageFormat.format("byteDepth={0}", byteDepth);
logger.severe(msg);
throw new IllegalStateException(msg);
}
}
/**
* Copies the contents of the composition buffer to the output buffer,
* converting the pixel format as necessary.
*
* @param out the output buffer
* @throws IllegalArgumentException if the buffer has an unsupported color
* depth
*/
@Override
void copyToBuffer(ByteBuffer out) {
bb.clear();
switch (byteDepth) {
case Byte.BYTES: {
if (lineByteBuffer == null) {
lineByteBuffer = ByteBuffer.allocate(width * Byte.BYTES);
lineByteBuffer.order(ByteOrder.nativeOrder());
linePixelBuffer = lineByteBuffer.duplicate();
}
IntBuffer srcPixels = bb.asIntBuffer();
ByteBuffer byteBuffer = (ByteBuffer) linePixelBuffer;
for (int y = 0; y < height; y++) {
byteBuffer.clear();
for (int x = 0; x < width; x++) {
copyNextPixel(srcPixels, byteBuffer);
}
lineByteBuffer.clear();
out.put(lineByteBuffer);
}
break;
}
case Short.BYTES: {
if (lineByteBuffer == null) {
lineByteBuffer = ByteBuffer.allocate(width * Short.BYTES);
lineByteBuffer.order(ByteOrder.nativeOrder());
linePixelBuffer = lineByteBuffer.asShortBuffer();
}
IntBuffer srcPixels = bb.asIntBuffer();
ShortBuffer shortBuffer = (ShortBuffer) linePixelBuffer;
for (int y = 0; y < height; y++) {
shortBuffer.clear();
for (int x = 0; x < width; x++) {
copyNextPixel(srcPixels, shortBuffer);
}
lineByteBuffer.clear();
out.put(lineByteBuffer);
}
break;
}
case Integer.BYTES: {
out.put(bb);
break;
}
default:
String msg = MessageFormat.format("byteDepth={0}", byteDepth);
logger.severe(msg);
throw new IllegalStateException(msg);
}
}
@Override
public String toString() {
return MessageFormat.format("{0}[width={1} height={2} depth={3} bb={4}]",
getClass().getName(), width, height, bitDepth, bb);
}
}