gecko-dev/gfx/thebes/gfxContext.cpp

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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* 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/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Oracle Corporation code.
*
* The Initial Developer of the Original Code is Oracle Corporation.
* Portions created by the Initial Developer are Copyright (C) 2005
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Stuart Parmenter <pavlov@pavlov.net>
* Vladimir Vukicevic <vladimir@pobox.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifdef _MSC_VER
#define _USE_MATH_DEFINES
#endif
#include <math.h>
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
#include "cairo.h"
#include "gfxContext.h"
#include "gfxColor.h"
#include "gfxMatrix.h"
#include "gfxASurface.h"
#include "gfxPattern.h"
#include "gfxPlatform.h"
#include "gfxTeeSurface.h"
gfxContext::gfxContext(gfxASurface *surface) :
mSurface(surface)
{
MOZ_COUNT_CTOR(gfxContext);
mCairo = cairo_create(surface->CairoSurface());
mFlags = surface->GetDefaultContextFlags();
}
gfxContext::~gfxContext()
{
cairo_destroy(mCairo);
MOZ_COUNT_DTOR(gfxContext);
}
gfxASurface *
gfxContext::OriginalSurface()
{
return mSurface;
}
already_AddRefed<gfxASurface>
gfxContext::CurrentSurface(gfxFloat *dx, gfxFloat *dy)
{
cairo_surface_t *s = cairo_get_group_target(mCairo);
if (s == mSurface->CairoSurface()) {
if (dx && dy)
cairo_surface_get_device_offset(s, dx, dy);
gfxASurface *ret = mSurface;
NS_ADDREF(ret);
return ret;
}
if (dx && dy)
cairo_surface_get_device_offset(s, dx, dy);
return gfxASurface::Wrap(s);
}
void
gfxContext::Save()
{
cairo_save(mCairo);
}
void
gfxContext::Restore()
{
cairo_restore(mCairo);
}
// drawing
void
gfxContext::NewPath()
{
cairo_new_path(mCairo);
}
void
gfxContext::ClosePath()
{
cairo_close_path(mCairo);
}
already_AddRefed<gfxPath> gfxContext::CopyPath() const
{
nsRefPtr<gfxPath> path = new gfxPath(cairo_copy_path(mCairo));
return path.forget();
}
void gfxContext::AppendPath(gfxPath* path)
{
if (path->mPath->status == CAIRO_STATUS_SUCCESS && path->mPath->num_data != 0)
cairo_append_path(mCairo, path->mPath);
}
gfxPoint
gfxContext::CurrentPoint() const
{
double x, y;
cairo_get_current_point(mCairo, &x, &y);
return gfxPoint(x, y);
}
void
gfxContext::Stroke()
{
cairo_stroke_preserve(mCairo);
}
void
gfxContext::Fill()
{
cairo_fill_preserve(mCairo);
}
void
gfxContext::FillWithOpacity(gfxFloat aOpacity)
{
// This method exists in the hope that one day cairo gets a direct
// API for this, and then we would change this method to use that
// API instead.
if (aOpacity != 1.0) {
gfxContextAutoSaveRestore saveRestore(this);
Clip();
Paint(aOpacity);
} else {
Fill();
}
}
void
gfxContext::MoveTo(const gfxPoint& pt)
{
cairo_move_to(mCairo, pt.x, pt.y);
}
void
gfxContext::NewSubPath()
{
cairo_new_sub_path(mCairo);
}
void
gfxContext::LineTo(const gfxPoint& pt)
{
cairo_line_to(mCairo, pt.x, pt.y);
}
void
gfxContext::CurveTo(const gfxPoint& pt1, const gfxPoint& pt2, const gfxPoint& pt3)
{
cairo_curve_to(mCairo, pt1.x, pt1.y, pt2.x, pt2.y, pt3.x, pt3.y);
}
void
gfxContext::QuadraticCurveTo(const gfxPoint& pt1, const gfxPoint& pt2)
{
double cx, cy;
cairo_get_current_point(mCairo, &cx, &cy);
cairo_curve_to(mCairo,
(cx + pt1.x * 2.0) / 3.0,
(cy + pt1.y * 2.0) / 3.0,
(pt1.x * 2.0 + pt2.x) / 3.0,
(pt1.y * 2.0 + pt2.y) / 3.0,
pt2.x,
pt2.y);
}
void
gfxContext::Arc(const gfxPoint& center, gfxFloat radius,
gfxFloat angle1, gfxFloat angle2)
{
cairo_arc(mCairo, center.x, center.y, radius, angle1, angle2);
}
void
gfxContext::NegativeArc(const gfxPoint& center, gfxFloat radius,
gfxFloat angle1, gfxFloat angle2)
{
cairo_arc_negative(mCairo, center.x, center.y, radius, angle1, angle2);
}
void
gfxContext::Line(const gfxPoint& start, const gfxPoint& end)
{
MoveTo(start);
LineTo(end);
}
// XXX snapToPixels is only valid when snapping for filled
// rectangles and for even-width stroked rectangles.
// For odd-width stroked rectangles, we need to offset x/y by
// 0.5...
void
gfxContext::Rectangle(const gfxRect& rect, PRBool snapToPixels)
{
if (snapToPixels) {
gfxRect snappedRect(rect);
if (UserToDevicePixelSnapped(snappedRect, PR_TRUE))
{
cairo_matrix_t mat;
cairo_get_matrix(mCairo, &mat);
cairo_identity_matrix(mCairo);
Rectangle(snappedRect);
cairo_set_matrix(mCairo, &mat);
return;
}
}
cairo_rectangle(mCairo, rect.X(), rect.Y(), rect.Width(), rect.Height());
}
void
gfxContext::Ellipse(const gfxPoint& center, const gfxSize& dimensions)
{
gfxSize halfDim = dimensions / 2.0;
gfxRect r(center - gfxPoint(halfDim.width, halfDim.height), dimensions);
gfxCornerSizes c(halfDim, halfDim, halfDim, halfDim);
RoundedRectangle (r, c);
}
void
gfxContext::Polygon(const gfxPoint *points, PRUint32 numPoints)
{
if (numPoints == 0)
return;
cairo_move_to(mCairo, points[0].x, points[0].y);
for (PRUint32 i = 1; i < numPoints; ++i) {
cairo_line_to(mCairo, points[i].x, points[i].y);
}
}
void
gfxContext::DrawSurface(gfxASurface *surface, const gfxSize& size)
{
cairo_save(mCairo);
cairo_set_source_surface(mCairo, surface->CairoSurface(), 0, 0);
cairo_new_path(mCairo);
// pixel-snap this
Rectangle(gfxRect(gfxPoint(0.0, 0.0), size), PR_TRUE);
cairo_fill(mCairo);
cairo_restore(mCairo);
}
// transform stuff
void
gfxContext::Translate(const gfxPoint& pt)
{
cairo_translate(mCairo, pt.x, pt.y);
}
void
gfxContext::Scale(gfxFloat x, gfxFloat y)
{
cairo_scale(mCairo, x, y);
}
void
gfxContext::Rotate(gfxFloat angle)
{
cairo_rotate(mCairo, angle);
}
void
gfxContext::Multiply(const gfxMatrix& matrix)
{
const cairo_matrix_t& mat = reinterpret_cast<const cairo_matrix_t&>(matrix);
cairo_transform(mCairo, &mat);
}
void
gfxContext::SetMatrix(const gfxMatrix& matrix)
{
const cairo_matrix_t& mat = reinterpret_cast<const cairo_matrix_t&>(matrix);
cairo_set_matrix(mCairo, &mat);
}
void
gfxContext::IdentityMatrix()
{
cairo_identity_matrix(mCairo);
}
gfxMatrix
gfxContext::CurrentMatrix() const
{
cairo_matrix_t mat;
cairo_get_matrix(mCairo, &mat);
return gfxMatrix(*reinterpret_cast<gfxMatrix*>(&mat));
}
void
gfxContext::NudgeCurrentMatrixToIntegers()
{
cairo_matrix_t mat;
cairo_get_matrix(mCairo, &mat);
gfxMatrix(*reinterpret_cast<gfxMatrix*>(&mat)).NudgeToIntegers();
cairo_set_matrix(mCairo, &mat);
}
gfxPoint
gfxContext::DeviceToUser(const gfxPoint& point) const
{
gfxPoint ret = point;
cairo_device_to_user(mCairo, &ret.x, &ret.y);
return ret;
}
gfxSize
gfxContext::DeviceToUser(const gfxSize& size) const
{
gfxSize ret = size;
cairo_device_to_user_distance(mCairo, &ret.width, &ret.height);
return ret;
}
gfxRect
gfxContext::DeviceToUser(const gfxRect& rect) const
{
gfxRect ret = rect;
cairo_device_to_user(mCairo, &ret.x, &ret.y);
cairo_device_to_user_distance(mCairo, &ret.width, &ret.height);
return ret;
}
gfxPoint
gfxContext::UserToDevice(const gfxPoint& point) const
{
gfxPoint ret = point;
cairo_user_to_device(mCairo, &ret.x, &ret.y);
return ret;
}
gfxSize
gfxContext::UserToDevice(const gfxSize& size) const
{
gfxSize ret = size;
cairo_user_to_device_distance(mCairo, &ret.width, &ret.height);
return ret;
}
gfxRect
gfxContext::UserToDevice(const gfxRect& rect) const
{
double xmin = rect.X(), ymin = rect.Y(), xmax = rect.XMost(), ymax = rect.YMost();
double x[3], y[3];
x[0] = xmin; y[0] = ymax;
x[1] = xmax; y[1] = ymax;
x[2] = xmax; y[2] = ymin;
cairo_user_to_device(mCairo, &xmin, &ymin);
xmax = xmin;
ymax = ymin;
for (int i = 0; i < 3; i++) {
cairo_user_to_device(mCairo, &x[i], &y[i]);
xmin = NS_MIN(xmin, x[i]);
xmax = NS_MAX(xmax, x[i]);
ymin = NS_MIN(ymin, y[i]);
ymax = NS_MAX(ymax, y[i]);
}
return gfxRect(xmin, ymin, xmax - xmin, ymax - ymin);
}
PRBool
gfxContext::UserToDevicePixelSnapped(gfxRect& rect, PRBool ignoreScale) const
{
if (GetFlags() & FLAG_DISABLE_SNAPPING)
return PR_FALSE;
// if we're not at 1.0 scale, don't snap, unless we're
// ignoring the scale. If we're not -just- a scale,
// never snap.
const gfxFloat epsilon = 0.0000001;
#define WITHIN_E(a,b) (fabs((a)-(b)) < epsilon)
cairo_matrix_t mat;
cairo_get_matrix(mCairo, &mat);
if (!ignoreScale &&
(!WITHIN_E(mat.xx,1.0) || !WITHIN_E(mat.yy,1.0) ||
!WITHIN_E(mat.xy,0.0) || !WITHIN_E(mat.yx,0.0)))
return PR_FALSE;
#undef WITHIN_E
gfxPoint p1 = UserToDevice(rect.TopLeft());
gfxPoint p2 = UserToDevice(rect.TopRight());
gfxPoint p3 = UserToDevice(rect.BottomRight());
// Check that the rectangle is axis-aligned. For an axis-aligned rectangle,
// two opposite corners define the entire rectangle. So check if
// the axis-aligned rectangle with opposite corners p1 and p3
// define an axis-aligned rectangle whose other corners are p2 and p4.
// We actually only need to check one of p2 and p4, since an affine
// transform maps parallelograms to parallelograms.
if (p2 == gfxPoint(p1.x, p3.y) || p2 == gfxPoint(p3.x, p1.y)) {
p1.Round();
p3.Round();
rect.MoveTo(gfxPoint(NS_MIN(p1.x, p3.x), NS_MIN(p1.y, p3.y)));
rect.SizeTo(gfxSize(NS_MAX(p1.x, p3.x) - rect.X(),
NS_MAX(p1.y, p3.y) - rect.Y()));
return PR_TRUE;
}
return PR_FALSE;
}
PRBool
gfxContext::UserToDevicePixelSnapped(gfxPoint& pt, PRBool ignoreScale) const
{
if (GetFlags() & FLAG_DISABLE_SNAPPING)
return PR_FALSE;
// if we're not at 1.0 scale, don't snap, unless we're
// ignoring the scale. If we're not -just- a scale,
// never snap.
cairo_matrix_t mat;
cairo_get_matrix(mCairo, &mat);
if ((!ignoreScale && (mat.xx != 1.0 || mat.yy != 1.0)) ||
(mat.xy != 0.0 || mat.yx != 0.0))
return PR_FALSE;
pt = UserToDevice(pt);
pt.Round();
return PR_TRUE;
}
void
gfxContext::PixelSnappedRectangleAndSetPattern(const gfxRect& rect,
gfxPattern *pattern)
{
gfxRect r(rect);
// Bob attempts to pixel-snap the rectangle, and returns true if
// the snapping succeeds. If it does, we need to set up an
// identity matrix, because the rectangle given back is in device
// coordinates.
//
// We then have to call a translate to dr.pos afterwards, to make
// sure the image lines up in the right place with our pixel
// snapped rectangle.
//
// If snapping wasn't successful, we just translate to where the
// pattern would normally start (in app coordinates) and do the
// same thing.
gfxMatrix mat = CurrentMatrix();
if (UserToDevicePixelSnapped(r)) {
IdentityMatrix();
}
Translate(r.TopLeft());
r.MoveTo(gfxPoint(0, 0));
Rectangle(r);
SetPattern(pattern);
SetMatrix(mat);
}
void
gfxContext::SetAntialiasMode(AntialiasMode mode)
{
if (mode == MODE_ALIASED) {
cairo_set_antialias(mCairo, CAIRO_ANTIALIAS_NONE);
} else if (mode == MODE_COVERAGE) {
cairo_set_antialias(mCairo, CAIRO_ANTIALIAS_DEFAULT);
}
}
gfxContext::AntialiasMode
gfxContext::CurrentAntialiasMode() const
{
cairo_antialias_t aa = cairo_get_antialias(mCairo);
if (aa == CAIRO_ANTIALIAS_NONE)
return MODE_ALIASED;
return MODE_COVERAGE;
}
void
gfxContext::SetDash(gfxLineType ltype)
{
static double dash[] = {5.0, 5.0};
static double dot[] = {1.0, 1.0};
switch (ltype) {
case gfxLineDashed:
SetDash(dash, 2, 0.0);
break;
case gfxLineDotted:
SetDash(dot, 2, 0.0);
break;
case gfxLineSolid:
default:
SetDash(nsnull, 0, 0.0);
break;
}
}
void
gfxContext::SetDash(gfxFloat *dashes, int ndash, gfxFloat offset)
{
cairo_set_dash(mCairo, dashes, ndash, offset);
}
//void getDash() const;
void
gfxContext::SetLineWidth(gfxFloat width)
{
cairo_set_line_width(mCairo, width);
}
gfxFloat
gfxContext::CurrentLineWidth() const
{
return cairo_get_line_width(mCairo);
}
void
gfxContext::SetOperator(GraphicsOperator op)
{
if (mFlags & FLAG_SIMPLIFY_OPERATORS) {
if (op != OPERATOR_SOURCE &&
op != OPERATOR_CLEAR &&
op != OPERATOR_OVER)
op = OPERATOR_OVER;
}
cairo_set_operator(mCairo, (cairo_operator_t)op);
}
gfxContext::GraphicsOperator
gfxContext::CurrentOperator() const
{
return (GraphicsOperator)cairo_get_operator(mCairo);
}
void
gfxContext::SetLineCap(GraphicsLineCap cap)
{
cairo_set_line_cap(mCairo, (cairo_line_cap_t)cap);
}
gfxContext::GraphicsLineCap
gfxContext::CurrentLineCap() const
{
return (GraphicsLineCap)cairo_get_line_cap(mCairo);
}
void
gfxContext::SetLineJoin(GraphicsLineJoin join)
{
cairo_set_line_join(mCairo, (cairo_line_join_t)join);
}
gfxContext::GraphicsLineJoin
gfxContext::CurrentLineJoin() const
{
return (GraphicsLineJoin)cairo_get_line_join(mCairo);
}
void
gfxContext::SetMiterLimit(gfxFloat limit)
{
cairo_set_miter_limit(mCairo, limit);
}
gfxFloat
gfxContext::CurrentMiterLimit() const
{
return cairo_get_miter_limit(mCairo);
}
void
gfxContext::SetFillRule(FillRule rule)
{
cairo_set_fill_rule(mCairo, (cairo_fill_rule_t)rule);
}
gfxContext::FillRule
gfxContext::CurrentFillRule() const
{
return (FillRule)cairo_get_fill_rule(mCairo);
}
// clipping
void
gfxContext::Clip(const gfxRect& rect)
{
cairo_new_path(mCairo);
cairo_rectangle(mCairo, rect.X(), rect.Y(), rect.Width(), rect.Height());
cairo_clip(mCairo);
}
void
gfxContext::Clip()
{
cairo_clip_preserve(mCairo);
}
void
gfxContext::ResetClip()
{
cairo_reset_clip(mCairo);
}
void
gfxContext::UpdateSurfaceClip()
{
NewPath();
// we paint an empty rectangle to ensure the clip is propagated to
// the destination surface
SetDeviceColor(gfxRGBA(0,0,0,0));
Rectangle(gfxRect(0,1,1,0));
Fill();
}
gfxRect
gfxContext::GetClipExtents()
{
double xmin, ymin, xmax, ymax;
cairo_clip_extents(mCairo, &xmin, &ymin, &xmax, &ymax);
return gfxRect(xmin, ymin, xmax - xmin, ymax - ymin);
}
// rendering sources
void
gfxContext::SetColor(const gfxRGBA& c)
{
if (gfxPlatform::GetCMSMode() == eCMSMode_All) {
gfxRGBA cms;
gfxPlatform::TransformPixel(c, cms, gfxPlatform::GetCMSRGBTransform());
// Use the original alpha to avoid unnecessary float->byte->float
// conversion errors
cairo_set_source_rgba(mCairo, cms.r, cms.g, cms.b, c.a);
}
else
cairo_set_source_rgba(mCairo, c.r, c.g, c.b, c.a);
}
void
gfxContext::SetDeviceColor(const gfxRGBA& c)
{
cairo_set_source_rgba(mCairo, c.r, c.g, c.b, c.a);
}
PRBool
gfxContext::GetDeviceColor(gfxRGBA& c)
{
return cairo_pattern_get_rgba(cairo_get_source(mCairo),
&c.r,
&c.g,
&c.b,
&c.a) == CAIRO_STATUS_SUCCESS;
}
void
gfxContext::SetSource(gfxASurface *surface, const gfxPoint& offset)
{
NS_ASSERTION(surface->GetAllowUseAsSource(), "Surface not allowed to be used as source!");
cairo_set_source_surface(mCairo, surface->CairoSurface(), offset.x, offset.y);
}
void
gfxContext::SetPattern(gfxPattern *pattern)
{
cairo_set_source(mCairo, pattern->CairoPattern());
}
already_AddRefed<gfxPattern>
gfxContext::GetPattern()
{
cairo_pattern_t *pat = cairo_get_source(mCairo);
NS_ASSERTION(pat, "I was told this couldn't be null");
gfxPattern *wrapper = nsnull;
if (pat)
wrapper = new gfxPattern(pat);
else
wrapper = new gfxPattern(gfxRGBA(0,0,0,0));
NS_IF_ADDREF(wrapper);
return wrapper;
}
// masking
void
gfxContext::Mask(gfxPattern *pattern)
{
cairo_mask(mCairo, pattern->CairoPattern());
}
void
gfxContext::Mask(gfxASurface *surface, const gfxPoint& offset)
{
cairo_mask_surface(mCairo, surface->CairoSurface(), offset.x, offset.y);
}
void
gfxContext::Paint(gfxFloat alpha)
{
cairo_paint_with_alpha(mCairo, alpha);
}
// groups
void
gfxContext::PushGroup(gfxASurface::gfxContentType content)
{
cairo_push_group_with_content(mCairo, (cairo_content_t) content);
}
static gfxRect
GetRoundOutDeviceClipExtents(gfxContext* aCtx)
{
gfxContextMatrixAutoSaveRestore save(aCtx);
aCtx->IdentityMatrix();
gfxRect r = aCtx->GetClipExtents();
r.RoundOut();
return r;
}
/**
* Copy the contents of aSrc to aDest, translated by aTranslation.
*/
static void
CopySurface(gfxASurface* aSrc, gfxASurface* aDest, const gfxPoint& aTranslation)
{
cairo_t *cr = cairo_create(aDest->CairoSurface());
cairo_set_source_surface(cr, aSrc->CairoSurface(), aTranslation.x, aTranslation.y);
cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
cairo_paint(cr);
cairo_destroy(cr);
}
void
gfxContext::PushGroupAndCopyBackground(gfxASurface::gfxContentType content)
{
if (content == gfxASurface::CONTENT_COLOR_ALPHA &&
!(GetFlags() & FLAG_DISABLE_COPY_BACKGROUND)) {
nsRefPtr<gfxASurface> s = CurrentSurface();
if ((s->GetAllowUseAsSource() || s->GetType() == gfxASurface::SurfaceTypeTee) &&
(s->GetContentType() == gfxASurface::CONTENT_COLOR ||
s->GetOpaqueRect().Contains(GetRoundOutDeviceClipExtents(this)))) {
cairo_push_group_with_content(mCairo, CAIRO_CONTENT_COLOR);
nsRefPtr<gfxASurface> d = CurrentSurface();
if (d->GetType() == gfxASurface::SurfaceTypeTee) {
NS_ASSERTION(s->GetType() == gfxASurface::SurfaceTypeTee, "Mismatched types");
nsAutoTArray<nsRefPtr<gfxASurface>,2> ss;
nsAutoTArray<nsRefPtr<gfxASurface>,2> ds;
static_cast<gfxTeeSurface*>(s.get())->GetSurfaces(&ss);
static_cast<gfxTeeSurface*>(d.get())->GetSurfaces(&ds);
NS_ASSERTION(ss.Length() == ds.Length(), "Mismatched lengths");
gfxPoint translation = d->GetDeviceOffset() - s->GetDeviceOffset();
for (PRUint32 i = 0; i < ss.Length(); ++i) {
CopySurface(ss[i], ds[i], translation);
}
} else {
CopySurface(s, d, gfxPoint(0, 0));
}
d->SetOpaqueRect(s->GetOpaqueRect());
return;
}
}
cairo_push_group_with_content(mCairo, (cairo_content_t) content);
}
already_AddRefed<gfxPattern>
gfxContext::PopGroup()
{
cairo_pattern_t *pat = cairo_pop_group(mCairo);
gfxPattern *wrapper = new gfxPattern(pat);
cairo_pattern_destroy(pat);
NS_IF_ADDREF(wrapper);
return wrapper;
}
void
gfxContext::PopGroupToSource()
{
cairo_pop_group_to_source(mCairo);
}
PRBool
gfxContext::PointInFill(const gfxPoint& pt)
{
return cairo_in_fill(mCairo, pt.x, pt.y);
}
PRBool
gfxContext::PointInStroke(const gfxPoint& pt)
{
return cairo_in_stroke(mCairo, pt.x, pt.y);
}
gfxRect
gfxContext::GetUserPathExtent()
{
double xmin, ymin, xmax, ymax;
cairo_path_extents(mCairo, &xmin, &ymin, &xmax, &ymax);
return gfxRect(xmin, ymin, xmax - xmin, ymax - ymin);
}
gfxRect
gfxContext::GetUserFillExtent()
{
double xmin, ymin, xmax, ymax;
cairo_fill_extents(mCairo, &xmin, &ymin, &xmax, &ymax);
return gfxRect(xmin, ymin, xmax - xmin, ymax - ymin);
}
gfxRect
gfxContext::GetUserStrokeExtent()
{
double xmin, ymin, xmax, ymax;
cairo_stroke_extents(mCairo, &xmin, &ymin, &xmax, &ymax);
return gfxRect(xmin, ymin, xmax - xmin, ymax - ymin);
}
already_AddRefed<gfxFlattenedPath>
gfxContext::GetFlattenedPath()
{
gfxFlattenedPath *path =
new gfxFlattenedPath(cairo_copy_path_flat(mCairo));
NS_IF_ADDREF(path);
return path;
}
PRBool
gfxContext::HasError()
{
return cairo_status(mCairo) != CAIRO_STATUS_SUCCESS;
}
void
gfxContext::RoundedRectangle(const gfxRect& rect,
const gfxCornerSizes& corners,
PRBool draw_clockwise)
{
//
// For CW drawing, this looks like:
//
// ...******0** 1 C
// ****
// *** 2
// **
// *
// *
// 3
// *
// *
//
// Where 0, 1, 2, 3 are the control points of the Bezier curve for
// the corner, and C is the actual corner point.
//
// At the start of the loop, the current point is assumed to be
// the point adjacent to the top left corner on the top
// horizontal. Note that corner indices start at the top left and
// continue clockwise, whereas in our loop i = 0 refers to the top
// right corner.
//
// When going CCW, the control points are swapped, and the first
// corner that's drawn is the top left (along with the top segment).
//
// There is considerable latitude in how one chooses the four
// control points for a Bezier curve approximation to an ellipse.
// For the overall path to be continuous and show no corner at the
// endpoints of the arc, points 0 and 3 must be at the ends of the
// straight segments of the rectangle; points 0, 1, and C must be
// collinear; and points 3, 2, and C must also be collinear. This
// leaves only two free parameters: the ratio of the line segments
// 01 and 0C, and the ratio of the line segments 32 and 3C. See
// the following papers for extensive discussion of how to choose
// these ratios:
//
// Dokken, Tor, et al. "Good approximation of circles by
// curvature-continuous Bezier curves." Computer-Aided
// Geometric Design 7(1990) 33--41.
// Goldapp, Michael. "Approximation of circular arcs by cubic
// polynomials." Computer-Aided Geometric Design 8(1991) 227--238.
// Maisonobe, Luc. "Drawing an elliptical arc using polylines,
// quadratic, or cubic Bezier curves."
// http://www.spaceroots.org/documents/ellipse/elliptical-arc.pdf
//
// We follow the approach in section 2 of Goldapp (least-error,
// Hermite-type approximation) and make both ratios equal to
//
// 2 2 + n - sqrt(2n + 28)
// alpha = - * ---------------------
// 3 n - 4
//
// where n = 3( cbrt(sqrt(2)+1) - cbrt(sqrt(2)-1) ).
//
// This is the result of Goldapp's equation (10b) when the angle
// swept out by the arc is pi/2, and the parameter "a-bar" is the
// expression given immediately below equation (21).
//
// Using this value, the maximum radial error for a circle, as a
// fraction of the radius, is on the order of 0.2 x 10^-3.
// Neither Dokken nor Goldapp discusses error for a general
// ellipse; Maisonobe does, but his choice of control points
// follows different constraints, and Goldapp's expression for
// 'alpha' gives much smaller radial error, even for very flat
// ellipses, than Maisonobe's equivalent.
//
// For the various corners and for each axis, the sign of this
// constant changes, or it might be 0 -- it's multiplied by the
// appropriate multiplier from the list before using.
const gfxFloat alpha = 0.55191497064665766025;
typedef struct { gfxFloat a, b; } twoFloats;
twoFloats cwCornerMults[4] = { { -1, 0 },
{ 0, -1 },
{ +1, 0 },
{ 0, +1 } };
twoFloats ccwCornerMults[4] = { { +1, 0 },
{ 0, -1 },
{ -1, 0 },
{ 0, +1 } };
twoFloats *cornerMults = draw_clockwise ? cwCornerMults : ccwCornerMults;
gfxPoint pc, p0, p1, p2, p3;
if (draw_clockwise)
cairo_move_to(mCairo, rect.X() + corners[NS_CORNER_TOP_LEFT].width, rect.Y());
else
cairo_move_to(mCairo, rect.X() + rect.Width() - corners[NS_CORNER_TOP_RIGHT].width, rect.Y());
NS_FOR_CSS_CORNERS(i) {
// the corner index -- either 1 2 3 0 (cw) or 0 3 2 1 (ccw)
mozilla::css::Corner c = mozilla::css::Corner(draw_clockwise ? ((i+1) % 4) : ((4-i) % 4));
// i+2 and i+3 respectively. These are used to index into the corner
// multiplier table, and were deduced by calculating out the long form
// of each corner and finding a pattern in the signs and values.
int i2 = (i+2) % 4;
int i3 = (i+3) % 4;
pc = rect.AtCorner(c);
if (corners[c].width > 0.0 && corners[c].height > 0.0) {
p0.x = pc.x + cornerMults[i].a * corners[c].width;
p0.y = pc.y + cornerMults[i].b * corners[c].height;
p3.x = pc.x + cornerMults[i3].a * corners[c].width;
p3.y = pc.y + cornerMults[i3].b * corners[c].height;
p1.x = p0.x + alpha * cornerMults[i2].a * corners[c].width;
p1.y = p0.y + alpha * cornerMults[i2].b * corners[c].height;
p2.x = p3.x - alpha * cornerMults[i3].a * corners[c].width;
p2.y = p3.y - alpha * cornerMults[i3].b * corners[c].height;
cairo_line_to (mCairo, p0.x, p0.y);
cairo_curve_to (mCairo,
p1.x, p1.y,
p2.x, p2.y,
p3.x, p3.y);
} else {
cairo_line_to (mCairo, pc.x, pc.y);
}
}
cairo_close_path (mCairo);
}