Context2D Example▲
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#ifndef CONTEXT2D_H
#define CONTEXT2D_H
#include "domimage.h"
#include <QPainter>
#include <QPainterPath>
#include <QString>
#include <QStack>
#include <QMetaType>
#include <QTimerEvent>
// [3]
class CanvasGradient
{
public:
CanvasGradient(const QGradient &v)
: value(v) {}
CanvasGradient() {}
QGradient value;
};
// [3]
Q_DECLARE_METATYPE(CanvasGradient)
Q_DECLARE_METATYPE(CanvasGradient*)
class ImageData {
};
class QContext2DCanvas;
class Context2D : public QObject
{
Q_OBJECT
// compositing
Q_PROPERTY(qreal globalAlpha READ globalAlpha WRITE setGlobalAlpha)
Q_PROPERTY(QString globalCompositeOperation READ globalCompositeOperation WRITE setGlobalCompositeOperation)
Q_PROPERTY(QVariant strokeStyle READ strokeStyle WRITE setStrokeStyle)
Q_PROPERTY(QVariant fillStyle READ fillStyle WRITE setFillStyle)
// line caps/joins
Q_PROPERTY(qreal lineWidth READ lineWidth WRITE setLineWidth)
Q_PROPERTY(QString lineCap READ lineCap WRITE setLineCap)
Q_PROPERTY(QString lineJoin READ lineJoin WRITE setLineJoin)
Q_PROPERTY(qreal miterLimit READ miterLimit WRITE setMiterLimit)
// shadows
Q_PROPERTY(qreal shadowOffsetX READ shadowOffsetX WRITE setShadowOffsetX)
Q_PROPERTY(qreal shadowOffsetY READ shadowOffsetY WRITE setShadowOffsetY)
Q_PROPERTY(qreal shadowBlur READ shadowBlur WRITE setShadowBlur)
Q_PROPERTY(QString shadowColor READ shadowColor WRITE setShadowColor)
public:
Context2D(QObject *parent = 0);
void setSize(int width, int height);
void setSize(const QSize &size);
QSize size() const;
void clear();
void reset();
// compositing
qreal globalAlpha() const; // (default 1.0)
QString globalCompositeOperation() const; // (default over)
QVariant strokeStyle() const; // (default black)
QVariant fillStyle() const; // (default black)
void setGlobalAlpha(qreal alpha);
void setGlobalCompositeOperation(const QString &op);
void setStrokeStyle(const QVariant &style);
void setFillStyle(const QVariant &style);
// line caps/joins
qreal lineWidth() const; // (default 1)
QString lineCap() const; // "butt", "round", "square" (default "butt")
QString lineJoin() const; // "round", "bevel", "miter" (default "miter")
qreal miterLimit() const; // (default 10)
void setLineWidth(qreal w);
void setLineCap(const QString &s);
void setLineJoin(const QString &s);
void setMiterLimit(qreal m);
// shadows
qreal shadowOffsetX() const; // (default 0)
qreal shadowOffsetY() const; // (default 0)
qreal shadowBlur() const; // (default 0)
QString shadowColor() const; // (default black)
void setShadowOffsetX(qreal x);
void setShadowOffsetY(qreal y);
void setShadowBlur(qreal b);
void setShadowColor(const QString &str);
public slots:
void save(); // push state on state stack
void restore(); // pop state stack and restore state
void scale(qreal x, qreal y);
void rotate(qreal angle);
void translate(qreal x, qreal y);
void transform(qreal m11, qreal m12, qreal m21, qreal m22,
qreal dx, qreal dy);
void setTransform(qreal m11, qreal m12, qreal m21, qreal m22,
qreal dx, qreal dy);
CanvasGradient createLinearGradient(qreal x0, qreal y0,
qreal x1, qreal y1);
CanvasGradient createRadialGradient(qreal x0, qreal y0,
qreal r0, qreal x1,
qreal y1, qreal r1);
// rects
void clearRect(qreal x, qreal y, qreal w, qreal h);
void fillRect(qreal x, qreal y, qreal w, qreal h);
void strokeRect(qreal x, qreal y, qreal w, qreal h);
// path API
void beginPath();
void closePath();
void moveTo(qreal x, qreal y);
void lineTo(qreal x, qreal y);
void quadraticCurveTo(qreal cpx, qreal cpy, qreal x, qreal y);
void bezierCurveTo(qreal cp1x, qreal cp1y,
qreal cp2x, qreal cp2y, qreal x, qreal y);
void arcTo(qreal x1, qreal y1, qreal x2, qreal y2, qreal radius);
void rect(qreal x, qreal y, qreal w, qreal h);
void arc(qreal x, qreal y, qreal radius,
qreal startAngle, qreal endAngle,
bool anticlockwise);
void fill();
void stroke();
void clip();
bool isPointInPath(qreal x, qreal y) const;
// drawing images
void drawImage(DomImage *image, qreal dx, qreal dy);
void drawImage(DomImage *image, qreal dx, qreal dy,
qreal dw, qreal dh);
void drawImage(DomImage *image, qreal sx, qreal sy,
qreal sw, qreal sh, qreal dx, qreal dy,
qreal dw, qreal dh);
// pixel manipulation
ImageData getImageData(qreal sx, qreal sy, qreal sw, qreal sh);
void putImageData(ImageData image, qreal dx, qreal dy);
signals:
void changed(const QImage &image);
protected:
void timerEvent(QTimerEvent *e);
private:
void beginPainting();
const QImage &endPainting();
void scheduleChange();
int m_changeTimerId;
QImage m_image;
QPainter m_painter;
QPainterPath m_path;
enum DirtyFlag {
DirtyTransformationMatrix = 0x00001,
DirtyClippingRegion = 0x00002,
DirtyStrokeStyle = 0x00004,
DirtyFillStyle = 0x00008,
DirtyGlobalAlpha = 0x00010,
DirtyLineWidth = 0x00020,
DirtyLineCap = 0x00040,
DirtyLineJoin = 0x00080,
DirtyMiterLimit = 0x00100,
MDirtyPen = DirtyStrokeStyle
| DirtyLineWidth
| DirtyLineCap
| DirtyLineJoin
| DirtyMiterLimit,
DirtyShadowOffsetX = 0x00200,
DirtyShadowOffsetY = 0x00400,
DirtyShadowBlur = 0x00800,
DirtyShadowColor = 0x01000,
DirtyGlobalCompositeOperation = 0x2000,
DirtyFont = 0x04000,
DirtyTextAlign = 0x08000,
DirtyTextBaseline = 0x10000,
AllIsFullOfDirt = 0xfffff
};
struct State {
State() : flags(0) {}
QMatrix matrix;
QPainterPath clipPath;
QBrush strokeStyle;
QBrush fillStyle;
qreal globalAlpha;
qreal lineWidth;
Qt::PenCapStyle lineCap;
Qt::PenJoinStyle lineJoin;
qreal miterLimit;
qreal shadowOffsetX;
qreal shadowOffsetY;
qreal shadowBlur;
QColor shadowColor;
QPainter::CompositionMode globalCompositeOperation;
QFont font;
int textAlign;
int textBaseline;
int flags;
};
State m_state;
QStack<State> m_stateStack;
};
#endif