jna-master/contrib/platform/src/com/sun/jna/platform/win32/GDI32Util.java
/* Copyright (c) 2015 Michael Freeman, All Rights Reserved
 *
 * The contents of this file is dual-licensed under 2
 * alternative Open Source/Free licenses: LGPL 2.1 or later and
 * Apache License 2.0. (starting with JNA version 4.0.0).
 *
 * You can freely decide which license you want to apply to
 * the project.
 *
 * You may obtain a copy of the LGPL License at:
 *
 * http://www.gnu.org/licenses/licenses.html
 *
 * A copy is also included in the downloadable source code package
 * containing JNA, in file "LGPL2.1".
 *
 * You may obtain a copy of the Apache License at:
 *
 * http://www.apache.org/licenses/
 *
 * A copy is also included in the downloadable source code package
 * containing JNA, in file "AL2.0".
 */
package com.sun.jna.platform.win32;

import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.awt.image.DataBuffer;
import java.awt.image.DataBufferInt;
import java.awt.image.DirectColorModel;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;

import com.sun.jna.Memory;
import com.sun.jna.Native;
import com.sun.jna.platform.win32.GDI32;
import com.sun.jna.platform.win32.User32;
import com.sun.jna.platform.win32.Win32Exception;
import com.sun.jna.platform.win32.WinDef.HBITMAP;
import com.sun.jna.platform.win32.WinDef.HDC;
import com.sun.jna.platform.win32.WinDef.HWND;
import com.sun.jna.platform.win32.WinDef.RECT;
import com.sun.jna.platform.win32.WinError;
import com.sun.jna.platform.win32.WinGDI;
import com.sun.jna.platform.win32.WinGDI.BITMAPINFO;
import com.sun.jna.platform.win32.WinNT.HANDLE;

/**
 * GDI32 utility API.
 *
 * @author mlfreeman[at]gmail.com
 */
public class GDI32Util {

    private static final DirectColorModel SCREENSHOT_COLOR_MODEL = new DirectColorModel(24, 0x00FF0000, 0xFF00, 0xFF);
    private static final int[] SCREENSHOT_BAND_MASKS = {
        SCREENSHOT_COLOR_MODEL.getRedMask(),
        SCREENSHOT_COLOR_MODEL.getGreenMask(),
        SCREENSHOT_COLOR_MODEL.getBlueMask()
    };

    /**
     * Takes a screenshot of the given window
     *
     * @param target The window to target
     *
     * @return the window captured as a screenshot, or null if the BufferedImage
     *         doesn't construct properly
     *
     * @throws IllegalStateException if the rectangle from GetWindowRect has a
     *                               width and/or height of 0. <br>
     * if the device context acquired from the original HWND doesn't release
     * properly
     */
    public static BufferedImage getScreenshot(HWND target) {
        RECT rect = new RECT();
        if (!User32.INSTANCE.GetWindowRect(target, rect)) {
            throw new Win32Exception(Native.getLastError());
        }
        Rectangle jRectangle = rect.toRectangle();
        int windowWidth = jRectangle.width;
        int windowHeight = jRectangle.height;

        if (windowWidth == 0 || windowHeight == 0) {
            throw new IllegalStateException("Window width and/or height were 0 even though GetWindowRect did not appear to fail.");
        }

        HDC hdcTarget = User32.INSTANCE.GetDC(target);
        if (hdcTarget == null) {
            throw new Win32Exception(Native.getLastError());
        }

        Win32Exception we = null;

        // device context used for drawing
        HDC hdcTargetMem = null;

        // handle to the bitmap to be drawn to
        HBITMAP hBitmap = null;

        // original display surface associated with the device context
        HANDLE hOriginal = null;

        // final java image structure we're returning.
        BufferedImage image = null;

        try {
            hdcTargetMem = GDI32.INSTANCE.CreateCompatibleDC(hdcTarget);
            if (hdcTargetMem == null) {
                throw new Win32Exception(Native.getLastError());
            }

            hBitmap = GDI32.INSTANCE.CreateCompatibleBitmap(hdcTarget, windowWidth, windowHeight);
            if (hBitmap == null) {
                throw new Win32Exception(Native.getLastError());
            }

            hOriginal = GDI32.INSTANCE.SelectObject(hdcTargetMem, hBitmap);
            if (hOriginal == null) {
                throw new Win32Exception(Native.getLastError());
            }

            // draw to the bitmap
            if (!GDI32.INSTANCE.BitBlt(hdcTargetMem, 0, 0, windowWidth, windowHeight, hdcTarget, 0, 0, GDI32.SRCCOPY)) {
                throw new Win32Exception(Native.getLastError());
            }

            BITMAPINFO bmi = new BITMAPINFO();
            bmi.bmiHeader.biWidth = windowWidth;
            bmi.bmiHeader.biHeight = -windowHeight;
            bmi.bmiHeader.biPlanes = 1;
            bmi.bmiHeader.biBitCount = 32;
            bmi.bmiHeader.biCompression = WinGDI.BI_RGB;

            Memory buffer = new Memory(windowWidth * windowHeight * 4);
            int resultOfDrawing = GDI32.INSTANCE.GetDIBits(hdcTarget, hBitmap, 0, windowHeight, buffer, bmi,
                    WinGDI.DIB_RGB_COLORS);
            if (resultOfDrawing == 0 || resultOfDrawing == WinError.ERROR_INVALID_PARAMETER) {
                throw new Win32Exception(Native.getLastError());
            }

            int bufferSize = windowWidth * windowHeight;
            DataBuffer dataBuffer = new DataBufferInt(buffer.getIntArray(0, bufferSize), bufferSize);
            WritableRaster raster = Raster.createPackedRaster(dataBuffer, windowWidth, windowHeight, windowWidth,
                    SCREENSHOT_BAND_MASKS, null);
            image = new BufferedImage(SCREENSHOT_COLOR_MODEL, raster, false, null);

        } catch (Win32Exception e) {
            we = e;
        } finally {
            if (hOriginal != null) {
                // per MSDN, set the display surface back when done drawing
                HANDLE result = GDI32.INSTANCE.SelectObject(hdcTargetMem, hOriginal);
                // failure modes are null or equal to HGDI_ERROR
                if (result == null || WinGDI.HGDI_ERROR.equals(result)) {
                    Win32Exception ex = new Win32Exception(Native.getLastError());
                    if (we != null) {
                        ex.addSuppressedReflected(we);
                    }
                    we = ex;
                }
            }

            if (hBitmap != null) {
                if (!GDI32.INSTANCE.DeleteObject(hBitmap)) {
                    Win32Exception ex = new Win32Exception(Native.getLastError());
                    if (we != null) {
                        ex.addSuppressedReflected(we);
                    }
                    we = ex;
                }
            }

            if (hdcTargetMem != null) {
                // get rid of the device context when done
                if (!GDI32.INSTANCE.DeleteDC(hdcTargetMem)) {
                    Win32Exception ex = new Win32Exception(Native.getLastError());
                    if (we != null) {
                        ex.addSuppressedReflected(we);
                    }
                    we = ex;
                }
            }

            if (hdcTarget != null) {
                if (0 == User32.INSTANCE.ReleaseDC(target, hdcTarget)) {
                    throw new IllegalStateException("Device context did not release properly.");
                }
            }
        }

        if (we != null) {
            throw we;
        }
        return image;
    }
}
