Objet canevas HTML DOM
Objet de toile
La balise HTML5 <canvas> est utilisée pour dessiner des graphiques, à la volée, avec JavaScript.
Accéder à un objet Canvas
Vous pouvez accéder à un élément <canvas> en utilisant getElementById() :
Exemple
var x = document.getElementById("myCanvas");
Créer un objet Canvas
Vous pouvez créer un élément <canvas> en utilisant la méthode document.createElement() :
Exemple
var x = document.createElement("CANVAS");
Remarque : L'élément <canvas> n'a pas de capacité de dessin propre (il s'agit uniquement d'un conteneur pour les graphiques) - vous devez utiliser un script pour dessiner les graphiques.
La méthode getContext() renvoie un objet qui fournit des méthodes et des propriétés pour dessiner sur le canevas.
Cette référence couvrira les propriétés et les méthodes de l'objet getContext("2d"), qui peut être utilisé pour dessiner du texte, des lignes, des boîtes, des cercles, etc. - sur le canevas.
Couleurs, styles et ombres
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 |
Styles de ligne
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 |
rectangles
Chemins
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 from that point to 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 |
Transformations
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() |
Texte
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 |
Dessin d'images
Method |
Description |
drawImage() |
Draws an image, canvas, or video onto the canvas |
Manipulation de pixels
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 |
Composition
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 |
Autre
Method |
Description |
save() |
Saves the state of the current context |
restore() |
Returns previously saved path state and attributes |
createEvent() |
|
getContext() |
|
toDataURL() |
|
Propriétés et événements standard
L'objet canevas prend également en charge les propriétés et les événements standard .
Pages connexes
Tutoriel HTML : HTML5 Canvas
Référence HTML : balise HTML <canvas>