HTML canvas globalCompositeOperation Property
Voorbeeld
Teken rechthoeken met twee verschillende globalCompositeOperation-waarden. Rode rechthoeken zijn bestemmingsafbeeldingen . Blauwe rechthoeken zijn bronafbeeldingen :
source-over
bestemming-over
javascript:
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.fillStyle = "red";
ctx.fillRect(20, 20, 75, 50);
ctx.globalCompositeOperation = "source-over";
ctx.fillStyle = "blue";
ctx.fillRect(50, 50, 75, 50);
ctx.fillStyle = "red";
ctx.fillRect(150, 20, 75, 50);
ctx.globalCompositeOperation = "destination-over";
ctx.fillStyle = "blue";
ctx.fillRect(180, 50, 75, 50);
Browserondersteuning
Internet Explorer 9, Firefox, Opera, Chrome en Safari ondersteunen de eigenschap globalCompositeOperation.
Definitie en gebruik
De eigenschap globalCompositeOperation bepaalt of retourneert hoe een (nieuwe) bronafbeelding op een (bestaande) doelafbeelding wordt getekend.
source image = tekeningen die je op het canvas gaat plaatsen.
bestemmingsafbeelding = tekeningen die al op het canvas zijn geplaatst.
Standaardwaarde: | source-over |
---|---|
JavaScript-syntaxis: | context .globalCompositeOperation="bron-in"; |
Eigendomswaarden
Value | Description | Play it |
---|---|---|
source-over | Default. Displays the source image over the destination image | |
source-atop | Displays the source image on top of the destination image. The part of the source image that is outside the destination image is not shown | |
source-in | Displays the source image in to the destination image. Only the part of the source image that is INSIDE the destination image is shown, and the destination image is transparent | |
source-out | Displays the source image out of the destination image. Only the part of the source image that is OUTSIDE the destination image is shown, and the destination image is transparent | |
destination-over | Displays the destination image over the source image | |
destination-atop | Displays the destination image on top of the source image. The part of the destination image that is outside the source image is not shown | |
destination-in | Displays the destination image in to the source image. Only the part of the destination image that is INSIDE the source image is shown, and the source image is transparent | |
destination-out | Displays the destination image out of the source image. Only the part of the destination image that is OUTSIDE the source image is shown, and the source image is transparent | |
lighter | Displays the source image + the destination image | |
copy | Displays the source image. The destination image is ignored | |
xor | The source image is combined by using an exclusive OR with the destination image |
Voorbeeld
Alle globalCompositeOperation-eigenschapswaarden: