cairo-win32-font.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):
 */

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

#ifndef SPI_GETFONTSMOOTHINGTYPE
#define SPI_GETFONTSMOOTHINGTYPE 0x200a
#endif
#ifndef FE_FONTSMOOTHINGCLEARTYPE
#define FE_FONTSMOOTHINGCLEARTYPE 2
#endif
#ifndef CLEARTYPE_QUALITY
#define CLEARTYPE_QUALITY 5
#endif
#ifndef TT_PRIM_CSPLINE
#define TT_PRIM_CSPLINE 3
#endif

const cairo_scaled_font_backend_t cairo_win32_scaled_font_backend;

typedef struct {
    cairo_scaled_font_t base;

    LOGFONTW logfont;

    BYTE quality;

    /* We do drawing and metrics computation in a "logical space" which
     * is similar to font space, except that it is scaled by a factor
     * of the (desired font size) * (WIN32_FONT_LOGICAL_SCALE). The multiplication
     * by WIN32_FONT_LOGICAL_SCALE allows for sub-pixel precision.
     */
    double logical_scale;

    /* The size we should actually request the font at from Windows; differs
     * from the logical_scale because it is quantized for orthogonal
     * transformations
     */
    double logical_size;

    /* Transformations from device <=> logical space
     */
    cairo_matrix_t logical_to_device;
    cairo_matrix_t device_to_logical;

    /* We special case combinations of 90-degree-rotations, scales and
     * flips ... that is transformations that take the axes to the
     * axes. If preserve_axes is true, then swap_axes/swap_x/swap_y
     * encode the 8 possibilities for orientation (4 rotation angles with
     * and without a flip), and scale_x, scale_y the scale components.
     */
    cairo_bool_t preserve_axes;
    cairo_bool_t swap_axes;
    cairo_bool_t swap_x;
    cairo_bool_t swap_y;
    double x_scale;
    double y_scale;

    /* The size of the design unit of the font
     */
    int em_square;

    HFONT scaled_hfont;
    HFONT unscaled_hfont;

    cairo_bool_t delete_scaled_hfont;
} cairo_win32_scaled_font_t;

static cairo_status_t
_cairo_win32_scaled_font_set_metrics (cairo_win32_scaled_font_t *scaled_font);

static cairo_status_t
_cairo_win32_scaled_font_init_glyph_metrics (cairo_win32_scaled_font_t *scaled_font,
					     cairo_scaled_glyph_t      *scaled_glyph);

static cairo_status_t
_cairo_win32_scaled_font_init_glyph_path (cairo_win32_scaled_font_t *scaled_font,
					  cairo_scaled_glyph_t      *scaled_glyph);

#define NEARLY_ZERO(d) (fabs(d) < (1. / 65536.))

static void
_compute_transform (cairo_win32_scaled_font_t *scaled_font,
		    cairo_matrix_t            *sc)
{
    cairo_status_t status;

    if (NEARLY_ZERO (sc->yx) && NEARLY_ZERO (sc->xy)) {
	scaled_font->preserve_axes = TRUE;
	scaled_font->x_scale = sc->xx;
	scaled_font->swap_x = (sc->xx < 0);
	scaled_font->y_scale = sc->yy;
	scaled_font->swap_y = (sc->yy < 0);
	scaled_font->swap_axes = FALSE;

    } else if (NEARLY_ZERO (sc->xx) && NEARLY_ZERO (sc->yy)) {
	scaled_font->preserve_axes = TRUE;
	scaled_font->x_scale = sc->yx;
	scaled_font->swap_x = (sc->yx < 0);
	scaled_font->y_scale = sc->xy;
	scaled_font->swap_y = (sc->xy < 0);
	scaled_font->swap_axes = TRUE;

    } else {
	scaled_font->preserve_axes = FALSE;
	scaled_font->swap_x = scaled_font->swap_y = scaled_font->swap_axes = FALSE;
    }

    if (scaled_font->preserve_axes) {
	if (scaled_font->swap_x)
	    scaled_font->x_scale = - scaled_font->x_scale;
	if (scaled_font->swap_y)
	    scaled_font->y_scale = - scaled_font->y_scale;

	scaled_font->logical_scale = WIN32_FONT_LOGICAL_SCALE * scaled_font->y_scale;
	scaled_font->logical_size = WIN32_FONT_LOGICAL_SCALE * floor (scaled_font->y_scale + 0.5);
    }

    /* The font matrix has x and y "scale" components which we extract and
     * use as character scale values.
     */
    cairo_matrix_init (&scaled_font->logical_to_device,
		       sc->xx, sc->yx, sc->xy, sc->yy, 0, 0);

    if (!scaled_font->preserve_axes) {
	_cairo_matrix_compute_scale_factors (&scaled_font->logical_to_device,
					     &scaled_font->x_scale, &scaled_font->y_scale,
					     TRUE);	/* XXX: Handle vertical text */

	scaled_font->logical_size = floor (WIN32_FONT_LOGICAL_SCALE * scaled_font->y_scale + 0.5);
	scaled_font->logical_scale = WIN32_FONT_LOGICAL_SCALE * scaled_font->y_scale;
    }

    cairo_matrix_scale (&scaled_font->logical_to_device,
			1.0 / scaled_font->logical_scale, 1.0 / scaled_font->logical_scale);

    scaled_font->device_to_logical = scaled_font->logical_to_device;

    status = cairo_matrix_invert (&scaled_font->device_to_logical);
    if (status)
	cairo_matrix_init_identity (&scaled_font->device_to_logical);
}

static cairo_bool_t
_have_cleartype_quality (void)
{
    OSVERSIONINFO version_info;

    version_info.dwOSVersionInfoSize = sizeof (OSVERSIONINFO);

    if (!GetVersionEx (&version_info)) {
	_cairo_win32_print_gdi_error ("_have_cleartype_quality");
	return FALSE;
    }

    return (version_info.dwMajorVersion > 5 ||
	    (version_info.dwMajorVersion == 5 &&
	     version_info.dwMinorVersion >= 1));	/* XP or newer */
}

static BYTE
_get_system_quality (void)
{
    BOOL font_smoothing;
    UINT smoothing_type;

    if (!SystemParametersInfo (SPI_GETFONTSMOOTHING, 0, &font_smoothing, 0)) {
	_cairo_win32_print_gdi_error ("_get_system_quality");
	return DEFAULT_QUALITY;
    }

    if (font_smoothing) {
	if (_have_cleartype_quality ()) {
	    if (!SystemParametersInfo (SPI_GETFONTSMOOTHINGTYPE,
				       0, &smoothing_type, 0)) {
		_cairo_win32_print_gdi_error ("_get_system_quality");
		return DEFAULT_QUALITY;
	    }

	    if (smoothing_type == FE_FONTSMOOTHINGCLEARTYPE)
		return CLEARTYPE_QUALITY;
	}

	return ANTIALIASED_QUALITY;
    } else {
	return DEFAULT_QUALITY;
    }
}

static cairo_scaled_font_t *
_win32_scaled_font_create (LOGFONTW                   *logfont,
			   HFONT                      hfont,
			   cairo_font_face_t	      *font_face,
			   const cairo_matrix_t       *font_matrix,
			   const cairo_matrix_t       *ctm,
			   const cairo_font_options_t *options)
{
    cairo_win32_scaled_font_t *f;
    cairo_matrix_t scale;
    cairo_status_t status;

    f = malloc (sizeof(cairo_win32_scaled_font_t));
    if (f == NULL)
	return NULL;

    f->logfont = *logfont;

    /* We don't have any control over the hinting style or subpixel
     * order in the Win32 font API, so we ignore those parts of
     * cairo_font_options_t. We use the 'antialias' field to set
     * the 'quality'.
     *
     * XXX: The other option we could pay attention to, but don't
     *      here is the hint_metrics options.
     */
    if (options->antialias == CAIRO_ANTIALIAS_DEFAULT)
	f->quality = _get_system_quality ();
    else {
	switch (options->antialias) {
	case CAIRO_ANTIALIAS_NONE:
	    f->quality = NONANTIALIASED_QUALITY;
	    break;
	case CAIRO_ANTIALIAS_GRAY:
	    f->quality = ANTIALIASED_QUALITY;
	    break;
	case CAIRO_ANTIALIAS_SUBPIXEL:
	    if (_have_cleartype_quality ())
		f->quality = CLEARTYPE_QUALITY;
	    else
		f->quality = ANTIALIASED_QUALITY;
	    break;
	case CAIRO_ANTIALIAS_DEFAULT:
	    ASSERT_NOT_REACHED;
	}
    }

    f->em_square = 0;
    f->scaled_hfont = hfont;
    f->unscaled_hfont = NULL;

    /* don't delete the hfont if it was passed in to us */
    f->delete_scaled_hfont = !hfont;

    cairo_matrix_multiply (&scale, font_matrix, ctm);
    _compute_transform (f, &scale);

    _cairo_scaled_font_init (&f->base, font_face,
			     font_matrix, ctm, options,
			     &cairo_win32_scaled_font_backend);

    status = _cairo_win32_scaled_font_set_metrics (f);
    if (status) {
	cairo_scaled_font_destroy (&f->base);
	return NULL;
    }

    return &f->base;
}

static cairo_status_t
_win32_scaled_font_set_world_transform (cairo_win32_scaled_font_t *scaled_font,
					HDC                        hdc)
{
    XFORM xform;

    xform.eM11 = scaled_font->logical_to_device.xx;
    xform.eM21 = scaled_font->logical_to_device.xy;
    xform.eM12 = scaled_font->logical_to_device.yx;
    xform.eM22 = scaled_font->logical_to_device.yy;
    xform.eDx = scaled_font->logical_to_device.x0;
    xform.eDy = scaled_font->logical_to_device.y0;

    if (!SetWorldTransform (hdc, &xform))
	return _cairo_win32_print_gdi_error ("_win32_scaled_font_set_world_transform");

    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_win32_scaled_font_set_identity_transform (HDC hdc)
{
    if (!ModifyWorldTransform (hdc, NULL, MWT_IDENTITY))
	return _cairo_win32_print_gdi_error ("_win32_scaled_font_set_identity_transform");

    return CAIRO_STATUS_SUCCESS;
}

static HDC
_get_global_font_dc (void)
{
    static HDC hdc;

    if (!hdc) {
	hdc = CreateCompatibleDC (NULL);
	if (!hdc) {
	    _cairo_win32_print_gdi_error ("_get_global_font_dc");
	    return NULL;
	}

	if (!SetGraphicsMode (hdc, GM_ADVANCED)) {
	    _cairo_win32_print_gdi_error ("_get_global_font_dc");
	    DeleteDC (hdc);
	    return NULL;
	}
    }

    return hdc;
}

static HFONT
_win32_scaled_font_get_scaled_hfont (cairo_win32_scaled_font_t *scaled_font)
{
    if (!scaled_font->scaled_hfont) {
	LOGFONTW logfont = scaled_font->logfont;
	logfont.lfHeight = -scaled_font->logical_size;
	logfont.lfWidth = 0;
	logfont.lfEscapement = 0;
	logfont.lfOrientation = 0;
	logfont.lfQuality = scaled_font->quality;

	scaled_font->scaled_hfont = CreateFontIndirectW (&logfont);
	if (!scaled_font->scaled_hfont) {
	    _cairo_win32_print_gdi_error ("_win32_scaled_font_get_scaled_hfont");
	    return NULL;
	}
    }

    return scaled_font->scaled_hfont;
}

static HFONT
_win32_scaled_font_get_unscaled_hfont (cairo_win32_scaled_font_t *scaled_font,
				       HDC                        hdc)
{
    if (!scaled_font->unscaled_hfont) {
	OUTLINETEXTMETRIC *otm;
	unsigned int otm_size;
	HFONT scaled_hfont;
	LOGFONTW logfont;

	scaled_hfont = _win32_scaled_font_get_scaled_hfont (scaled_font);
	if (!scaled_hfont)
	    return NULL;

	if (!SelectObject (hdc, scaled_hfont)) {
	    _cairo_win32_print_gdi_error ("_win32_scaled_font_get_unscaled_hfont:SelectObject");
	    return NULL;
	}

	otm_size = GetOutlineTextMetrics (hdc, 0, NULL);
	if (!otm_size) {
	    _cairo_win32_print_gdi_error ("_win32_scaled_font_get_unscaled_hfont:GetOutlineTextMetrics");
	    return NULL;
	}

	otm = malloc (otm_size);
	if (!otm)
	    return NULL;