Android canvas implementation and demo, android canvas demo
Today we bring you a simple implementation of the Android canvas function. The following is:
The following are the key source code:
import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Paint.Style;import andro
One drawback of the canvas's drawimage approach is that it will not work when the picture is not loaded.Of course, in the high-speed game main loop, you can ignore this problem directly, or use Img.complete = = True to make a judgment.In a place outside the game loop, you can use Img.onload = function () {}; this callback resolves.However, if you need to implement loading of a large number of images and inform the user of the loading progress, a picture loader is required.I. Picture Loader princ
Canvas Canvas in the mainstream browser size limit detailed introduction
The test found that canvas has different maximum size limits under different browsers.
As we all know, canvas has its own width,height properties to control the size, with CSS width,height, control the size of the display. Can be understood as
HTML5 canvas (deformation), html5 canvas Deformation
Coordinate Transformation
Case 1:
Note:
(1) Translation
Cxt. translate (x, y );
The translate method uses two parameters. x indicates the number of units to move the axis origin point to the left. The default value is pixel, and y indicates the number of units to move the axis origin point down.
(2) Expansion
Cxt. scale (x, y );
The scale met
Arc and ArcTo are similar from name to title. ArcTo is also a way of drawing curves, and the curves he draws are also arcs of a circle. But his parameters and arc are absolutely mortal.Ctx.arcto (X1,y1,x2,y2,radius), ArcTo's parameters include two points, and these two points do not represent the point of the center, only the last parameter is the radius of the circle, indicating that ArcTo and the circle have a little relationship.Online about ArcTo article very few, very hard to find an articl
Canvas: Specifies how to draw a video cover. canvas draws a cover.
I. Requirement: Upload a video and take a certain frame of the video as the video album art.
II. Implementation idea: Use the canvas Image Rendering function to draw an image frame. The first frame is drawn here, which is easy to implement.
Iii. Code:
The above is all the content of this article
Call the local camera to take pictures (H5 and canvas), and the camera to take pictures of the h5 canvas
Implementation of calling the local camera photo function for H5 and canvas
1. Code Implementation (html part))
2. js part
3. Implementation
4. browser Section
Camera method navigator is enabled for H5 photos. getUserMedia: tests are applicable to Fir
The non-zero surround principle in the canvas and the canvas zero surround Principle
Non-zero surround principle:If you need to determine whether a region needs to be filled with color, select a random point from the region.
Pull a straight line from this point and be sure to pull it out of the graph. At this time, the point is the center of the circle.The line that passes through the pulled straight line
[Original] a canvas written based on the new html5 label canvas, html5canvas
I recently learned canvas and wrote a small application exercise.
Source code
1
Running Effect
There are still some problems:
The actual painting position is different from the mouse position when the browser location is changed.
A breakpoint occurs when the mouse moves too fast.
Hope
Secondary Canvas drawing and secondary canvas drawing
For Canvas plotting, you can use the toDataURL () method to save the drawn image, and then provide it to the object element for secondary use.
Js Processing
Result:
Canvas first experience, canvas
The first time I tried to use canvas for a verification code
Next, let's go directly to the Code. There are comments in the code for your understanding:
Copyright Disclaimer: This article is an original article by the blogger and cannot be reproduced without the permission of the blogger.
Arc and ArcTo are similar from name to title. ArcTo is also a way of drawing curves, and the curves he draws are also arcs of a circle. But his parameters and arc are absolutely mortal.Ctx.arcto (X1,y1,x2,y2,radius);The ArcTo parameter includes two points, and the points in the two points do not represent the center point, only the last parameter is the radius of the circle, indicating that ArcTo and the circle have a little relationship.Online about ArcTo article very few, very hard to find an
The jsp page uses the canvas to generate an image of the page, click the problem of flashback, jsp canvas
Recently, I was working on a project and found a problem: I used canvas to combine html pages and watermarks into an image for display. The user pressed the image and saved the image to the mobile phone.
There is no problem with the Android mobile phone. Wh
rectangle with the canvasGet the Canvas objectvar Canvas1=document.getelementbyid ("First");Insert a brush to a canvasvar Cxt=canvas1.getcontext ("2d")Preparing to draw colorscxt.fillstyle= "Red"Fill Rectangle: The 4 parameters inside are the position of the X and Y axes, and W and H set the rectangle width height;Cxt.fillrect (0,0,100,100)Two rectangles overlapcxt.fillstyle= "Red"Cxt.fillrect (0,0,100,100)Cxt.fillstyle= "Blue"Cxt.fillrect (60,60,100
Canvas knowledge summary and canvas knowledge
1. Basic Knowledge
There are two ways to draw an image by using the canvas element:
Context. fill () // fill in context. stroke () // draw the border
Style: Set the style of the drawing before drawing.
Context. fillStyle // filled style context. strokeStyle // border style context. lineWidth // graphic Border Width
Co
Canvas BASICS (2) canvas Basics
Html section:
Part 1 save and restore the drawing statusIn the canvas, the drawing State refers to the complete set of attributes that describe the 2D rendering context appearance at a specific time point, from simple color values to complex transformation matrices and other featuresNote: The current path and the current Bitmap (d
Comments: Today, we will use canvas to create a letter-guessing game. The game design is very simple. The system will randomly select one of the 26 letters of a-z to save it. Enter a letter on your keyboard, the system will prompt you that the correct characters are smaller or larger than the ones currently entered, and the game will not end until you enter the correct letters, if you are interested, let's take a look at how to use
Comments: One of the difficulties in drawing curves in anvas is that there are four functions connected to curves! They are arc, arcTo, quadraticCurveTo, and bezierCurveTo. let me start with the simplest method of arc. If you are interested, you can find out. In the canvas Line Painting article, I talked about how to draw a straight line, this article on Curve painting should have been published. However, because
Canvas: move the mouse to draw the image. canvas: drag to draw the image.
You can use canvas to draw various images by dragging the mouse.This includes rectangles, circles, arrows, and brushes.
Usage
var paint = Ypaint(canvas)Draw a circle:
paint.chooseCircle()Other circular Parameters
Width of the circle: paint. outer
Canvas is drawn based on the turntable.For a look at Canvas's browser compatibility issues, as shown in. (from can I use)
Tips: Just take to IE8 under the test, what reaction is not, in advance set up, if the browser does not support the prompt is not prompted, the developer tool in the element code is nothing.
Html:Js:var canvas = document.getElementById ('
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