I'm creating a pixel art app and when I want to save the image from the canvas the image is so small, so it seems pixelated when I want to resize it.
I want to resize it to bigger dimensions, but I don't know how.
This is the code example:
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(0, 0, 50, 50);
ctx.fillStyle = 'red';
ctx.fill();
document.write('<img style="width:300px;" src="'+c.toDataURL("image/png")+'"/>');
// This is an image with dimensions 108x108px and it seems very bad when i resize it to 300x300px
// I want to download the canvas image with more resolution
<canvas id="myCanvas" width="108" height="108" style="width: 300px; height:300px;">
</canvas>
you can create a canvas and put the imageData in it.
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(0, 0, 25, 25);
ctx.fillStyle = 'red';
ctx.fill();
ctx.beginPath();
ctx.rect(0, 25, 25, 25);
ctx.fillStyle = 'yellow';
ctx.fill();
ctx.beginPath();
ctx.rect(25, 0, 25, 25);
ctx.fillStyle = 'blue';
ctx.fill();
ctx.beginPath();
ctx.rect(25, 25, 25, 25);
ctx.fillStyle = 'green';
ctx.fill();
var c2 = document.createElement("canvas");
c2.width = 50;
c2.height = 50;
var ctx2 = c2.getContext("2d");
var imageData = ctx.getImageData(0, 0, 50, 50);
ctx2.putImageData(imageData, 0, 0);
document.write('<img style="width:300px;" src="' + c2.toDataURL("image/png") + '"/>');
Related
I have two half-ellipses and I'm trying fill the space between them. For whatever reason the "fill" is getting "twisted" in the middle:
const canvas = document.getElementById("canvas"),
ctx = canvas.getContext("2d");
canvas.width = canvas.height = 300;
ctx.ellipse(150, 0, 150, 90, 0, 0, Math.PI);
ctx.ellipse(150, 200, 150, 90, 0, 0, Math.PI);
ctx.fillStyle = "lightgreen";
ctx.fill();
ctx.stroke();
<canvas id="canvas"></canvas>
Any ideas how to make it fill so it's like a cylinder (without far side on top)
I guess all it need was rotate one of the ellipses and draw it in reverse:
const canvas = document.getElementById("canvas"),
ctx = canvas.getContext("2d");
canvas.width = canvas.height = 300;
ctx.ellipse(150, 0, 150, 90, 0, 0, Math.PI);
ctx.ellipse(150, 200, 150, 90, Math.PI, 0, Math.PI, true); //changed
ctx.fillStyle = "lightgreen";
ctx.fill();
ctx.stroke();
<canvas id="canvas"></canvas>
i am trying to draw a canvas line on div id "myCanvas" but problem is the line becomes very low resolution and its not shows smooth line. How can i increase that line resolution? And make it smooth line?
js:
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
context.rect(0, 0, canvas.width, canvas.height);
var grd = context.createLinearGradient(100, 150, canvas.width, canvas.height);
grd.addColorStop(0, '#0132bf');
grd.addColorStop(1, '#ccd9ff');
context.fillStyle = grd;
context.fill();
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
context.beginPath();
context.lineTo(-10, 190);
context.bezierCurveTo(200, -100, 500, 200, 400, 150);
context.lineWidth = .9;
context.strokeStyle = '#ccd9ff';
context.stroke();
jsfiddle link
Try giving your canvas HTML element width and height attributes that fit your requirements, for example:
<canvas id="myCanvas" width="600" height="600">
I am trying to create below canvas.
Image
my code is below. but I am having trouble to make the canvas look the like the screenshot above. can anyone help me then?
thanks though
<html>
<canvas id="gameCanvas" width="800" height="600"></canvas>
<script>
var canvas;
var canvasContext;
window.onload = function() {
canvas = document.getElementById('gameCanvas');
canvasContext = canvas.getContext('2d');
canvasContext.fillStyle = 'blue';
canvasContext.fillRect(0,0,canvas.width,canvas.height);
canvasContext.fillStyle = 'grey';
canvasContext.fillRect(355,350,120,90);
canvasContext.fillStyle = 'grey';
canvasContext.fillRect(190,350,120,90);
canvasContext.fillStyle = 'grey';
canvasContext.fillRect(520,350,120,90);
canvasContext.fillStyle = 'grey';
canvasContext.fillRect(355,200,120,90);
canvasContext.fillStyle = 'grey';
canvasContext.fillRect(190,200,120,90);
canvasContext.fillStyle = 'grey';
canvasContext.fillRect(520,200,120,90);
}
</script>
</html>
.fillRect creates a filled region of color. However, .rect creates a "shape" that you can then use the .fill() and .stroke() methods upon.
In the below example if converted creation into a loop for brevity
var canvas;
var canvasContext;
window.onload = function() {
canvas = document.getElementById('gameCanvas');
canvasContext = canvas.getContext('2d');
canvasContext.fillStyle = 'blue';
canvasContext.fillRect(0,0,canvas.width,canvas.height);
var height = 90;
var width = 120;
var leftOffset = 190;
var topOffset = 200;
for(var x = 0; x < 6; x++){
canvasContext.beginPath();
canvasContext.rect(leftOffset,topOffset,width,height);
canvasContext.fillStyle = 'grey';
canvasContext.fill();
canvasContext.lineWidth = 4;
canvasContext.strokeStyle = 'lightblue';
canvasContext.stroke();
leftOffset += 165;
if(x === 2){
leftOffset = 190;
topOffset = 350;
}
}
}
JSFIDDLE
This tutorial on HTML5 Canvas rectangles is very handy
To add the text, you would append the following after (or before) the rect creating loop
canvasContext.beginPath();
canvasContext.font = '20pt Arial';
canvasContext.textAlign = 'center';
canvasContext.fillStyle = 'white';
canvasContext.shadowColor = 'black';
canvasContext.shadowOffsetX = 4;
canvasContext.shadowOffsetY = 4;
canvasContext.fillText('CHOOSE A SCENE TO COLOR', canvas.width/2,55);
UPDATED FIDDLE
Tutorials for text align, text shadow, and text.
Try something like this, use a function to draw a rectangle with exactly the border you want. The trick is to use .rect instead of fillRect so that you can use .stroke() immediately after.
<html>
<canvas id="gameCanvas" width="800" height="600"></canvas>
<script>
function draw_bordered_rect(context, x, y, w, h) {
context.rect(x, y, w, h);
context.fillStyle = "grey";
context.fill();
context.lineWidth = 3;
context.strokeStyle = "lightblue";
context.stroke();
}
window.onload = function() {
canvas = document.getElementById('gameCanvas');
canvasContext = canvas.getContext('2d');
canvasContext.fillStyle = 'blue';
canvasContext.fillRect(0, 0, canvas.width, canvas.height);
canvasContext.font = '25pt Arial';
canvasContext.textAlign = 'center';
//drop shadow 2px to the left and 2px below the white text
canvasContext.fillStyle = "black";
canvasContext.fillText('CHOOSE A SCENE TO COLOR', canvas.width/2-2, 82);
//actual text ontop of the drop shadow text
canvasContext.fillStyle = 'white';
canvasContext.fillText('CHOOSE A SCENE TO COLOR', canvas.width/2, 80);
draw_bordered_rect(canvasContext, 355, 350, 120, 90);
draw_bordered_rect(canvasContext, 190, 350, 120, 90);
draw_bordered_rect(canvasContext, 520, 350, 120, 90);
draw_bordered_rect(canvasContext, 355, 200, 120, 90);
draw_bordered_rect(canvasContext, 190, 200, 120, 90);
draw_bordered_rect(canvasContext, 520, 200, 120, 90);
}
</script>
</html>
Looks like:
I have some code to design canvas box in HTML5. I think you should try this one, I hope it will help you to design your canvas box. I think you should use JavaScript mehtod context.fillRect as i am giving you Js Fidler Lind here
HTML Code
<canvas id="myCanvas" width="500" height="400">
<!-- Insert fallback content here -->
</canvas>
JavaScript Code
var canvas = $("#myCanvas");
var context = canvas.get(0).getContext("2d");
// Set rectangle and corner values
var rectX = 50;
var rectY = 50;
var rectWidth = 100;
var rectHeight = 100;
var cornerRadius = 20;
// Reference rectangle without rounding, for size comparison
context.fillRect(200, 50, rectWidth, rectHeight);
// Set faux rounded corners
context.lineJoin = "round";
context.lineWidth = cornerRadius;
// Change origin and dimensions to match true size (a stroke makes the shape a bit larger)
context.strokeRect(rectX+(cornerRadius/2), rectY+(cornerRadius/2), rectWidth-cornerRadius, rectHeight-cornerRadius);
context.fillRect(rectX+(cornerRadius/2), rectY+(cornerRadius/2), rectWidth-cornerRadius, rectHeight-cornerRadius);
// You can do the same thing with paths, like this triangle
// Remember that a stroke will make the shape a bit larger so you'll need to fiddle with the
// coordinates to get the correct dimensions.
context.beginPath();
context.moveTo(400, 60);
context.lineTo(440, 140);
context.lineTo(360, 140);
context.closePath();
context.stroke();
context.fill();
This javascript code will design canvas box just like below g]iven image
I don´t know why the text in canvas is blurry and the image drawed is also blurry, this is my example how I create the canvas with the image and text.
https://jsfiddle.net/jorge182/5ju5pLqb/2/
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
var imageObj = new Image();
imageObj.onload = function() {
context.save();
context.beginPath();
context.arc(25, 25, 25, 0, Math.PI * 2, true);
context.closePath();
context.clip();
context.drawImage(imageObj, 0, 0, 50, 50);
context.beginPath();
context.arc(0, 0, 25, 0, Math.PI * 2, true);
context.clip();
context.closePath();
context.restore();
context.lineWidth = 2;
context.textAlign = 'left';
context.font = '8pt Signika Negative';
context.fillStyle = 'black';
context.fillText('Jorge', 60, 15);
context.fillText(' have been here!', 60, 30);
context.font = '6pt Signika Negative';
context.textAling = 'left';
context.fillStyle = '#555';
context.fillText('Caribe Photo Weading Photograpy', 60, 40);
};
imageObj.src = 'http://www.html5canvastutorials.com/demos/assets/darth-vader.jpg'
The blurry image is probably because you resized the image too much from its original size. Take a look at the jsFiddle below and you can see if you only resize half of its size it's still looking good.
https://jsfiddle.net/gracegotlost/5ju5pLqb/3/
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
var imageObj = new Image();
imageObj.src = 'http://www.html5canvastutorials.com/demos/assets/darth-vader.jpg';
imageObj.onload = function() {
var width = imageObj.width;
var height = imageObj.height;
context.save();
context.beginPath();
context.arc(width/2, height/2, 150, 0, Math.PI * 2, true);
context.fill();
context.closePath();
context.clip();
context.drawImage(imageObj, 0, 0, imageObj.width, imageObj.height);
context.beginPath();
context.arc(0, 0, 25, 0, Math.PI * 2, true);
context.clip();
context.closePath();
context.restore();
context.textAlign = 'left';
context.font = '32pt Signika Negative';
context.fillStyle = 'black';
context.fillText('Jorge', 60, 350);
context.fillText(' have been here!', 150, 350);
context.font = '20pt Signika Negative';
context.textAling = 'left';
context.fillStyle = '#555';
context.fillText('Caribe Photo Weading Photograpy', 60, 400);
};
For the blurry text I found one post very helpful. If you can increase the text size it will look better, but to give it even more higher resolution you would probably do as follows:
https://stackoverflow.com/a/15666143/4809052
For the jagged edge the first answer is very helpful.
Seemed simple enough to draw circles and text in an HTML5 canvas, but I get non-intuitive behavior. The circles get drawn nice and pretty, then the more circles I draw, the older circles become more and more octagonal shaped. Very strange to me... Also, the text disappears from the old circles and only appears on the last circle drawn. What's the proper way to do this with canvases?
$("#circles_container").on("click", "#circles_canvas", function(event) {
var canvas = document.getElementById('circles_canvas');
if (canvas.getContext) {
var ctx = canvas.getContext("2d");
var w = 16;
var x = event.pageX;
var y = Math.floor(event.pageY-$(this).offset().top);
ctx.fillStyle = "rgb(200,0,0)";
ctx.arc(x, y, w/2, 0, 2 * Math.PI, false);
ctx.fill();
ctx = canvas.getContext("2d");
ctx.font = '8pt Calibri';
ctx.fillStyle = 'white';
ctx.textAlign = 'center';
ctx.fillText('0', x, y+3);
}
});
Just add this near the start of your function :
ctx.beginPath();
You were drawing a path always longer.
Demo in Stack Snippets & JS Fiddle (click on the canvas)
var canvas = document.getElementById('circles_canvas');
canvas.addEventListener("click", function(event) {
if (canvas.getContext) {
var ctx = canvas.getContext("2d");
var w = 16;
var x = Math.floor(event.pageX-this.offsetLeft);
var y = Math.floor(event.pageY-this.offsetTop);
ctx.beginPath();
ctx.fillStyle = "rgb(200,0,0)";
ctx.arc(x, y, w/2, 0, 2 * Math.PI, false);
ctx.fill();
ctx.font = '8pt Calibri';
ctx.fillStyle = 'white';
ctx.textAlign = 'center';
ctx.fillText('0', x, y+3);
}
})
canvas {
border: 1px solid black;
}
<h1>Click Canvas Below</h1>
<canvas id="circles_canvas"></canvas>