ondraw

问题 I extended ViewPager to have a moving background (seems to be a fairly popular request too) It seems to be mostly working, the problem I have is that sometimes the whole background turns black. This actually specifically occurs when I rotate the screen while on another page than the first one and start moving (it is still ok after the screen rotation) - when the activity restarts after the screen rotation, it restores the ViewPager to the same page as it was before. The whole code with

问题 I extended ViewPager to have a moving background (seems to be a fairly popular request too) It seems to be mostly working, the problem I have is that sometimes the whole background turns black. This actually specifically occurs when I rotate the screen while on another page than the first one and start moving (it is still ok after the screen rotation) - when the activity restarts after the screen rotation, it restores the ViewPager to the same page as it was before. The whole code with

问题 I put a Log.d() call into the onDraw() of my extended View, so I could see how often and when it's getting called. It gets called upon instantiation of the view, which is not surprising. But then I notice, it gets called on every tap that is handled by onTouchEvent(), even though my code there isn't doing anything remotely related to graphics. However, in the documentation for Views, I can't seem to find anything about when onDraw() is actually called. I'm not really concerned about my

问题 I have a RoundRectShape that is drawn in a View 's onDraw() function. The corners of this shape are modified by any drag actions on this view through an overridden onTouchEvent function (which calls invalidate() to force the call to onDraw() ). When initialising variables in onDraw , Eclipse shows a warning saying Avoid object allocations during draw/layout operations (preallocate and reuse instead) . This issue is explained as follows: You should avoid allocating objects during a drawing or

问题 What I want to do: On mouse hover of Blurry image, it shows unblur same image in square shape like following image. (image is completely blur, on mouse hover unblur image shown in square shape) What I have done: I set blur image using following code (link) using PorterDuff.Mode. On touch of screen mouse pointer converted into square and image shows unblur. Edit: Problem: Now picture is unblur but i cant find proper blur effect on blurry image and unblur image is also not clear, on touch is

问题 I've got a little problem on a exercise of my class. The exercise is to draw Shapes multiple times on Canvas. But I can only draw once, when I draw another one, the previous is deleted. Here is my CustomView code. figuras is an LinkedList of shapes that in the future I will save them. On draw i shall sraw the figures from the LinkedList. package com.example.AndroidTest; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint

问题 I am very novice in android drawing and animation on android. I have a bar chart and I want to animate the bars (bottom-up drawing). I know that invalidate() within onDraw() is a good manner to do it but until now I fails to do it... import android.graphics.Path; import android.graphics.Region; public class Bar { private int color; private String name; private float value; private Path path; private Region region; public int getColor() { return color; } public void setColor(int color) { this

问题 I am trying to draw a oval using canvas, but it never gets drawn. Here is my code for the custom view. I have also used setWillNotDraw(false) still nothing gets drawn on the screen. public class Myview extends View { Paint paint; RectF rect; public Myview(Context context) { super(context); init(); setWillNotDraw(false); } public Myview(Context context, AttributeSet attrs) { super(context, attrs); init(); setWillNotDraw(false); } public Myview(Context context, AttributeSet attrs, int defStyle)

问题 I have tried so many methods but still my code refuses to simply draw a line on the canvas. Each of the attempts I have commented out either crash the program or won't display the line. I am really struggling to get my head around how to do this, I keep getting different advice on using threads or onDraw or whatever, but none seem to work. My overall objective is to display a bitmap image on the screen, and draw lines on top of it. I then wish to use canvas.tranlate to make the entire image

问题 I am new to Android Development and reading the book Hello Android . It uses a Sudoku example, and the code that I am referring to is here. In this , onTouchScreen, it calls select method, that calls invalidate twice. The question is that, on invalidating is the onDraw method called right after that? So will in this case, inside my select method, it will do invalidate call onDraw Do some stuff invalidate call onDraw Is this how it will happen, also, will the entire screen be regenerated? All