cairo-win32-surface.c

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

/* Cairo - a vector graphics library with display and print output
 *
 * Copyright © 2005 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it either under the terms of the GNU Lesser General Public
 * License version 2.1 as published by the Free Software Foundation
 * (the "LGPL") or, at your option, under the terms of the Mozilla
 * Public License Version 1.1 (the "MPL"). If you do not alter this
 * notice, a recipient may use your version of this file under either
 * the MPL or the LGPL.
 *
 * You should have received a copy of the LGPL along with this library
 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 * You should have received a copy of the MPL along with this library
 * in the file COPYING-MPL-1.1
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
 * the specific language governing rights and limitations.
 *
 * The Original Code is the cairo graphics library.
 *
 * The Initial Developer of the Original Code is Red Hat, Inc.
 *
 * Contributor(s):
 *	Owen Taylor <[e-mail]>
 *	Stuart Parmenter <[e-mail]>
 *	Vladimir Vukicevic <[e-mail]>
 */

#include <stdio.h>
#include "cairoint.h"
#include "cairo-clip-private.h"
#include "cairo-win32-private.h"

/* for older SDKs */
#ifndef SHADEBLENDCAPS
#define SHADEBLENDCAPS  120
#endif
#ifndef SB_NONE
#define SB_NONE         0x00000000
#endif

static const cairo_surface_backend_t cairo_win32_surface_backend;

/**
 * _cairo_win32_print_gdi_error:
 * @context: context string to display along with the error
 *
 * Helper function to dump out a human readable form of the
 * current error code.
 *
 * Return value: A cairo status code for the error code
 **/
cairo_status_t
_cairo_win32_print_gdi_error (const char *context)
{
    void *lpMsgBuf;
    DWORD last_error = GetLastError ();

    if (!FormatMessageA (FORMAT_MESSAGE_ALLOCATE_BUFFER |
			 FORMAT_MESSAGE_FROM_SYSTEM,
			 NULL,
			 last_error,
			 MAKELANGID (LANG_NEUTRAL, SUBLANG_DEFAULT),
			 (LPTSTR) &lpMsgBuf,
			 0, NULL)) {
	fprintf (stderr, "%s: Unknown GDI error", context);
    } else {
	fprintf (stderr, "%s: %s", context, (char *)lpMsgBuf);

	LocalFree (lpMsgBuf);
    }

    /* We should switch off of last_status, but we'd either return
     * CAIRO_STATUS_NO_MEMORY or CAIRO_STATUS_UNKNOWN_ERROR and there
     * is no CAIRO_STATUS_UNKNOWN_ERROR.
     */

    return CAIRO_STATUS_NO_MEMORY;
}

static cairo_status_t
_create_dc_and_bitmap (cairo_win32_surface_t *surface,
		       HDC                    original_dc,
		       cairo_format_t         format,
		       int                    width,
		       int                    height,
		       char                 **bits_out,
		       int                   *rowstride_out)
{
    cairo_status_t status;

    BITMAPINFO *bitmap_info = NULL;
    struct {
	BITMAPINFOHEADER bmiHeader;
	RGBQUAD bmiColors[2];
    } bmi_stack;
    void *bits;

    int num_palette = 0;	/* Quiet GCC */
    int i;

    surface->dc = NULL;
    surface->bitmap = NULL;

    switch (format) {
    case CAIRO_FORMAT_ARGB32:
    case CAIRO_FORMAT_RGB24:
	num_palette = 0;
	break;

    case CAIRO_FORMAT_A8:
	num_palette = 256;
	break;

    case CAIRO_FORMAT_A1:
	num_palette = 2;
	break;
    }

    if (num_palette > 2) {
	bitmap_info = malloc (sizeof (BITMAPINFOHEADER) + num_palette * sizeof (RGBQUAD));
	if (!bitmap_info)
	    return CAIRO_STATUS_NO_MEMORY;
    } else {
	bitmap_info = (BITMAPINFO *)&bmi_stack;
    }

    bitmap_info->bmiHeader.biSize = sizeof (BITMAPINFOHEADER);
    bitmap_info->bmiHeader.biWidth = width == 0 ? 1 : width;
    bitmap_info->bmiHeader.biHeight = height == 0 ? -1 : - height; /* top-down */
    bitmap_info->bmiHeader.biSizeImage = 0;
    bitmap_info->bmiHeader.biXPelsPerMeter = 72. / 0.0254; /* unused here */
    bitmap_info->bmiHeader.biYPelsPerMeter = 72. / 0.0254; /* unused here */
    bitmap_info->bmiHeader.biPlanes = 1;

    switch (format) {
    /* We can't create real RGB24 bitmaps because something seems to
     * break if we do, especially if we don't set up an image
     * fallback.  It could be a bug with using a 24bpp pixman image
     * (and creating one with masks).  So treat them like 32bpp.
     */
    case CAIRO_FORMAT_RGB24:
    case CAIRO_FORMAT_ARGB32:
	bitmap_info->bmiHeader.biBitCount = 32;
	bitmap_info->bmiHeader.biCompression = BI_RGB;
	bitmap_info->bmiHeader.biClrUsed = 0;	/* unused */
	bitmap_info->bmiHeader.biClrImportant = 0;
	break;

    case CAIRO_FORMAT_A8:
	bitmap_info->bmiHeader.biBitCount = 8;
	bitmap_info->bmiHeader.biCompression = BI_RGB;
	bitmap_info->bmiHeader.biClrUsed = 256;
	bitmap_info->bmiHeader.biClrImportant = 0;

	for (i = 0; i < 256; i++) {
	    bitmap_info->bmiColors[i].rgbBlue = i;
	    bitmap_info->bmiColors[i].rgbGreen = i;
	    bitmap_info->bmiColors[i].rgbRed = i;
	    bitmap_info->bmiColors[i].rgbReserved = 0;
	}

	break;

    case CAIRO_FORMAT_A1:
	bitmap_info->bmiHeader.biBitCount = 1;
	bitmap_info->bmiHeader.biCompression = BI_RGB;
	bitmap_info->bmiHeader.biClrUsed = 2;
	bitmap_info->bmiHeader.biClrImportant = 0;

	for (i = 0; i < 2; i++) {
	    bitmap_info->bmiColors[i].rgbBlue = i * 255;
	    bitmap_info->bmiColors[i].rgbGreen = i * 255;
	    bitmap_info->bmiColors[i].rgbRed = i * 255;
	    bitmap_info->bmiColors[i].rgbReserved = 0;
	    break;
	}
    }

    surface->dc = CreateCompatibleDC (original_dc);
    if (!surface->dc)
	goto FAIL;

    surface->bitmap = CreateDIBSection (surface->dc,
			                bitmap_info,
			                DIB_RGB_COLORS,
			                &bits,
			                NULL, 0);
    if (!surface->bitmap)
	goto FAIL;

    GdiFlush();

    surface->saved_dc_bitmap = SelectObject (surface->dc,
					     surface->bitmap);
    if (!surface->saved_dc_bitmap)
	goto FAIL;

    if (bitmap_info && num_palette > 2)
	free (bitmap_info);

    if (bits_out)
	*bits_out = bits;

    if (rowstride_out) {
	/* Windows bitmaps are padded to 32-bit (dword) boundaries */
	switch (format) {
	case CAIRO_FORMAT_ARGB32:
	case CAIRO_FORMAT_RGB24:
	    *rowstride_out = 4 * width;
	    break;

	case CAIRO_FORMAT_A8:
	    *rowstride_out = (width + 3) & ~3;
	    break;

	case CAIRO_FORMAT_A1:
	    *rowstride_out = ((width + 31) & ~31) / 8;
	    break;
	}
    }

    return CAIRO_STATUS_SUCCESS;

 FAIL:
    status = _cairo_win32_print_gdi_error ("_create_dc_and_bitmap");

    if (bitmap_info && num_palette > 2)
	free (bitmap_info);

    if (surface->saved_dc_bitmap) {
	SelectObject (surface->dc, surface->saved_dc_bitmap);
	surface->saved_dc_bitmap = NULL;
    }

    if (surface->bitmap) {
	DeleteObject (surface->bitmap);
	surface->bitmap = NULL;
    }

    if (surface->dc) {
 	DeleteDC (surface->dc);
	surface->dc = NULL;
    }

    return status;
}

static cairo_surface_t *
_cairo_win32_surface_create_for_dc (HDC             original_dc,
				    cairo_format_t  format,
				    int	            width,
				    int	            height)
{
    cairo_status_t status;
    cairo_win32_surface_t *surface;
    char *bits;
    int rowstride;

    surface = malloc (sizeof (cairo_win32_surface_t));
    if (surface == NULL) {
	_cairo_error (CAIRO_STATUS_NO_MEMORY);
	return &_cairo_surface_nil;
    }

    status = _create_dc_and_bitmap (surface, original_dc, format,
				    width, height,
				    &bits, &rowstride);
    if (status)
	goto FAIL;

    surface->image = cairo_image_surface_create_for_data (bits, format,
							  width, height, rowstride);
    if (surface->image->status) {
	status = CAIRO_STATUS_NO_MEMORY;
	goto FAIL;
    }

    surface->format = format;

    surface->clip_rect.x = 0;
    surface->clip_rect.y = 0;
    surface->clip_rect.width = width;
    surface->clip_rect.height = height;

    surface->saved_clip = CreateRectRgn (0, 0, 0, 0);
    if (GetClipRgn (surface->dc, surface->saved_clip) == 0) {
        DeleteObject(surface->saved_clip);
        surface->saved_clip = NULL;
    }

    surface->extents = surface->clip_rect;

    _cairo_surface_init (&surface->base, &cairo_win32_surface_backend,
			 _cairo_content_from_format (format));

    return (cairo_surface_t *)surface;

 FAIL:
    if (surface->bitmap) {
	SelectObject (surface->dc, surface->saved_dc_bitmap);
  	DeleteObject (surface->bitmap);
        DeleteDC (surface->dc);
    }
    if (surface)
	free (surface);

    if (status == CAIRO_STATUS_NO_MEMORY) {
	_cairo_error (CAIRO_STATUS_NO_MEMORY);
	return &_cairo_surface_nil;
    } else {
	_cairo_error (status);
	return &_cairo_surface_nil;
    }
}

static cairo_surface_t *
_cairo_win32_surface_create_similar (void	    *abstract_src,
				     cairo_content_t content,
				     int	     width,
				     int	     height)
{
    cairo_win32_surface_t *src = abstract_src;
    cairo_format_t format = _cairo_format_from_content (content);

    return _cairo_win32_surface_create_for_dc (src->dc, format, width, height);
}

static cairo_status_t
_cairo_win32_surface_finish (void *abstract_surface)
{
    cairo_win32_surface_t *surface = abstract_surface;

    if (surface->image)
	cairo_surface_destroy (surface->image);

    if (surface->saved_clip)
	DeleteObject (surface->saved_clip);

    /* If we created the Bitmap and DC, destroy them */
    if (surface->bitmap) {
	SelectObject (surface->dc, surface->saved_dc_bitmap);
  	DeleteObject (surface->bitmap);
        DeleteDC (surface->dc);
    }

    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_cairo_win32_surface_get_subimage (cairo_win32_surface_t  *surface,
				   int                     x,
				   int                     y,
				   int                     width,
				   int                     height,
				   cairo_win32_surface_t **local_out)
{
    cairo_win32_surface_t *local;
    cairo_status_t status;
    cairo_content_t content = _cairo_content_from_format (surface->format);

    local =
	(cairo_win32_surface_t *) _cairo_win32_surface_create_similar (surface,
								       content,
								       width,
								       height);
    if (local->base.status)
	return CAIRO_STATUS_NO_MEMORY;

    if (!BitBlt (local->dc,
		 0, 0,
		 width, height,
		 surface->dc,
		 x, y,
		 SRCCOPY)) {
	/* If we fail to BitBlt here, most likely the source is a printer.
	 * You can't reliably get bits from a printer DC, so just fill in
	 * the surface as white (common case for printing).
	 */

	RECT r;
	r.left = r.top = 0;
	r.right = width;
	r.bottom = height;
	FillRect(local->dc, &r, (HBRUSH)GetStockObject(WHITE_BRUSH));
    }

    *local_out = local;

    return CAIRO_STATUS_SUCCESS;

 FAIL:
    status = _cairo_win32_print_gdi_error ("_cairo_win32_surface_get_subimage");

    if (local)
	cairo_surface_destroy (&local->base);

    return status;
}

static cairo_status_t
_cairo_win32_surface_acquire_source_image (void                    *abstract_surface,
					   cairo_image_surface_t  **image_out,
					   void                   **image_extra)
{
    cairo_win32_surface_t *surface = abstract_surface;
    cairo_win32_surface_t *local = NULL;
    cairo_status_t status;

    if (surface->image) {
	*image_out = (cairo_image_surface_t *)surface->image;
	*image_extra = NULL;

	return CAIRO_STATUS_SUCCESS;
    }

    status = _cairo_win32_surface_get_subimage (abstract_surface, 0, 0,
						surface->clip_rect.width,
						surface->clip_rect.height, &local);
    if (status)
	return status;

    *image_out = (cairo_image_surface_t *)local->image;
    *image_extra = local;

    return CAIRO_STATUS_SUCCESS;