Odniesienie do płótna HTML
Opis
Znacznik HTML5 <canvas> służy do rysowania grafiki w locie za pomocą skryptów (zwykle JavaScript).
Jednak element <canvas> nie ma własnych możliwości rysowania (jest tylko pojemnikiem na grafikę) - musisz użyć skryptu, aby faktycznie narysować grafikę.
Metoda getContext() zwraca obiekt, który udostępnia metody i właściwości do rysowania na kanwie.
To odniesienie obejmie właściwości i metody obiektu getContext("2d"), których można użyć do rysowania tekstu, linii, prostokątów, okręgów i innych elementów na płótnie.
Obsługa przeglądarki
Liczby w tabeli określają pierwszą wersję przeglądarki, która w pełni obsługuje dany element.
Element |
|
|
|
|
|
<canvas> |
4.0 |
9.0 |
2.0 |
3.1 |
9.0 |
Internet Explorer 9, Firefox, Opera, Chrome i Safari obsługują <canvas> oraz ich właściwości i metody.
Uwaga: Internet Explorer 8 i wcześniejsze wersje nie obsługują elementu <canvas>.
Kolory, style i cienie
Property |
Description |
fillStyle |
Sets or returns the color, gradient, or pattern used to fill the drawing |
strokeStyle |
Sets or returns the color, gradient, or pattern used for strokes |
shadowColor |
Sets or returns the color to use for shadows |
shadowBlur |
Sets or returns the blur level for shadows |
shadowOffsetX |
Sets or returns the horizontal distance of the shadow from the shape |
shadowOffsetY |
Sets or returns the vertical distance of the shadow from the shape |
Style linii
Property |
Description |
lineCap |
Sets or returns the style of the end caps for a line |
lineJoin |
Sets or returns the type of corner created, when two lines meet |
lineWidth |
Sets or returns the current line width |
miterLimit |
Sets or returns the maximum miter length |
Prostokąty
Ścieżki
Method |
Description |
fill() |
Fills the current drawing (path) |
stroke() |
Actually draws the path you have defined |
beginPath() |
Begins a path, or resets the current path |
moveTo() |
Moves the path to the specified point in the canvas, without creating a
line |
closePath() |
Creates a path from the current point back to the starting point |
lineTo() |
Adds a new point and creates a line to that point from the last
specified point in the canvas |
clip() |
Clips a region of any shape and size from the original canvas |
quadraticCurveTo() |
Creates a quadratic Bézier curve |
bezierCurveTo() |
Creates a cubic Bézier curve |
arc() |
Creates an arc/curve (used to create circles, or parts of circles) |
arcTo() |
Creates an arc/curve between two tangents |
isPointInPath() |
Returns true if the specified point is in the current path, otherwise
false |
Transformacje
Method |
Description |
scale() |
Scales the current drawing bigger or smaller |
rotate() |
Rotates the current drawing |
translate() |
Remaps the (0,0) position on the canvas |
transform() |
Replaces the current transformation matrix for the drawing |
setTransform() |
Resets the current transform to the identity matrix. Then runs
transform() |
Tekst
Property |
Description |
font |
Sets or returns the current font properties for text content |
textAlign |
Sets or returns the current alignment for text content |
textBaseline |
Sets or returns the current text baseline used when drawing text |
Method |
Description |
fillText() |
Draws "filled" text on the canvas |
strokeText() |
Draws text on the canvas (no fill) |
measureText() |
Returns an object that contains the width of the specified text |
Rysunek obrazu
Method |
Description |
drawImage() |
Draws an image, canvas, or video onto the canvas |
Manipulacja pikselami
Property |
Description |
width |
Returns the width of an ImageData object |
height |
Returns the height of an ImageData object |
data |
Returns an object that contains image data of a specified ImageData
object |
Method |
Description |
createImageData() |
Creates a new, blank ImageData object |
getImageData() |
Returns an ImageData object that copies the pixel data for the specified
rectangle on a canvas |
putImageData() |
Puts the image data (from a specified ImageData object) back onto the
canvas |
Komponowanie
Property |
Description |
globalAlpha |
Sets or returns the current alpha or transparency value of the drawing |
globalCompositeOperation |
Sets or returns how a new image are drawn onto an existing image |
Inny
Method |
Description |
save() |
Saves the state of the current context |
restore() |
Returns previously saved path state and attributes |
createEvent() |
|
getContext() |
|
toDataURL() |
|