Tela HTML propriedade globalCompositeOperation
Exemplo
Desenhe retângulos usando dois valores globalCompositeOperation diferentes. Retângulos vermelhos são imagens de destino . Retângulos azuis são imagens de origem :
sobre-fonte
destino final
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);
Suporte ao navegador
Internet Explorer 9, Firefox, Opera, Chrome e Safari suportam a propriedade globalCompositeOperation.
Definição e uso
A propriedade globalCompositeOperation define ou retorna como uma imagem de origem (nova) é desenhada em uma imagem de destino (existente).
imagem de origem = desenhos que você está prestes a colocar na tela.
imagem de destino = desenhos que já estão colocados na tela.
| Valor padrão: | sobre-fonte |
|---|---|
| Sintaxe JavaScript: | context .globalCompositeOperation="source-in"; |
Valores de propriedade
| 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 |
Exemplo
Todos os valores da propriedade globalCompositeOperation: