i'm trying to generate a tile-based-map, which works just fine so far, but after replacing all the "test-rectangles" with images to represent the ground, the path, some houses etc. (in this case its the same image for all of them), not a single image gets drawn down.
What am i doing wrong here? I also get zero errors.
Heres the code snipped:
// generate a large map
Map.prototype.generate = function(){
var ctx = document.createElement("canvas").getContext("2d");
ctx.canvas.width = this.width;
ctx.canvas.height = this.height;
var rows = ~~(this.width/<?php echo $GAME['map']['tileSize'] + $GAME['map']['tileBorder']; ?>) + 1;
var columns = ~~(this.height/<?php echo $GAME['map']['tileSize'] + $GAME['map']['tileBorder']; ?>) + 1;
ctx.save();
// Here i wanted to check if the image gets drawn right besides the player
var testImage = document.createElement('img'); // Also tried new Image();
testImage.onload = (function () {
console.log(testImage + "-test");
ctx.drawImage(testImage, 1000, 1000, <?php echo $GAME['map']['tileSize']; ?>, <?php echo $GAME['map']['tileSize']; ?>);
}());
testImage.src = "http://192.168.0.140/img/terrain.png";
var imgs = [];
var imgIndex = 0;
<?php echo "for (var y = 0, i = ".$tilesToLoad['xStart']."; i < ".($tilesToLoad['xStart'] + $GAME['map']['chunkSize'])."; y+=".($GAME['map']['tileSize'] + $GAME['map']['tileBorder']).", i++) {"; ?>
<?php echo "for (var x = 0, j = ".$tilesToLoad['yStart']."; j < ".($tilesToLoad['yStart'] + $GAME['map']['chunkSize'])."; x+=".($GAME['map']['tileSize'] + $GAME['map']['tileBorder']).", j++) {"; ?>
imgs[imgIndex] = document.createElement('img');
imgs[imgIndex].onload = (function () {
console.log(imgs[imgIndex] + "-" + imgIndex + "-" + x + "-" + y);
ctx.drawImage(imgs[imgIndex], x, y, <?php echo $GAME['map']['tileSize']; ?>, <?php echo $GAME['map']['tileSize']; ?>);
}());
imgs[imgIndex].src = "http://192.168.0.140/img/terrain.png";
imgIndex += 1;
}
}
ctx.restore();
// store the generate map as this image texture
this.image = new Image();
this.image.src = ctx.canvas.toDataURL("image/png");
// clear context
ctx = null;
}
console.log output:
[object HTMLImageElement]-test
[object HTMLImageElement]-0-0-0
[object HTMLImageElement]-1-41-0
[object HTMLImageElement]-2-82-0
[object HTMLImageElement]-3-123-0
It is not having the desired effect because you have written the onload function as an IIFE . It is executing the function immediately, before the src is assigned, and onload is not getting assigned to the function.
Change the first onload assignment to this:
testImage.onload = function () {
console.log(testImage + "-test");
ctx.drawImage(testImage, 1000, 1000, <?php echo $GAME['map']['tileSize']; ?>, <?php echo $GAME['map']['tileSize']; ?>);
};
All I have done there is removed the outer brackets. And the same for the later assignment:
imgs[imgIndex].onload = function () {
console.log(imgs[imgIndex] + "-" + imgIndex + "-" + x + "-" + y);
ctx.drawImage(imgs[imgIndex], x, y, <?php echo $GAME['map']['tileSize']; ?>, <?php echo $GAME['map']['tileSize']; ?>);
};
I suggest removing the ctx = null;
assignment because if this executes before the onload events, then they will fail to draw the images on the canvas, instead you will get Uncaught TypeError: Cannot read property 'drawImage' of null
Also, as Blindman67 pointed out, a change is needed to get the image to be created from the canvas after all the onload events have fired. To do this you could perhaps use a counter, similar to this example where an alert is shown after a set of images are loaded.
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