关于canvas的save()及restore()步骤...- UIPopoverController的施用

当前位置: 编程技术>移动开发

本页文章导读:

▪关于canvas的save()及restore()步骤关于canvas的save()及restore()方法 import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.........

▪ UIPopoverController的施用 UIPopoverController的使用 UIPopoverController只能在ipad设备上面使用；作用是用于显示临时内容，特点是总是显示在当前视图最前端，当单击界面的其他地方时自动消失。UIViewController* vCtrl = [[UIVie.........

▪ IPAD 拖动事例(也支持鼠标) IPAD 拖动例子(也支持鼠标) <html><head> <title>iPad Touch Test</title> <meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=0"> <script src="http://ajax.googleapis.com/ajax/libs.........

[1]关于canvas的save()及restore()步骤

来源: 互联网发布时间: 2014-02-18

关于canvas的save()及restore()方法

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.SurfaceView;

public class MyView1 extends SurfaceView
{

	private Bitmap mBitmap;

	private Paint mPaint;

	public MyView1(Context context, AttributeSet attrs)
	{
		super(context, attrs);
		mPaint = new Paint();
		this.initBitmap();
	}

	private void initBitmap()
	{
		mBitmap = BitmapFactory.decodeResource(getResources(),
				R.drawable.ic_launcher);
	}

	@Override
	public void draw(Canvas canvas)
	{
		super.draw(canvas);

		mPaint.setColor(Color.BLUE);
		canvas.drawRect(100, 200, 200, 300, mPaint);

		canvas.save();
		canvas.rotate(45);
		mPaint.setColor(Color.RED);
		canvas.drawRect(150, 10, 200, 60, mPaint);
		canvas.restore();

		mPaint.setColor(Color.GREEN);
		canvas.drawRect(200, 10, 250, 100, mPaint);
	}

}

上图代码绘制出的view如下图：

如掉save和restore方法（38和42行），意味着绿色的图形也受到38和42行之间，对canvas操作的代码影响，也会旋转，如下图：

[2] UIPopoverController的施用

来源: 互联网发布时间: 2014-02-18

UIPopoverController的使用
UIPopoverController只能在ipad设备上面使用；作用是用于显示临时内容，特点是总是显示在当前视图最前端，当单击界面的其他地方时自动消失。
UIViewController* vCtrl = [[UIViewController alloc] init]; UIPopoverController*popController = [[UIPopoverController alloc] initWithContentViewController:vCtrl];   popController.popoverContentSize = CGSizeMake(320,480); CGrect rect =CGRectMake(0,0,2,2);   [popController presentPopoverFromRect:rect inView:aView permittedArrowDirections:UIPopoverArrowDirectionUp animated:YES];

在使用该控制器的时候，下面几个步骤是必须的：
1.UIPopoverController该控制器的内容必须由一个控制器提供；提供方式有三：
- (id)initWithContentViewController:(UIViewController *)viewController
@property (nonatomic, retain) UIViewController *contentViewController
- (void)setContentViewController:(UIViewController *)viewController animated:(BOOL)animated
2.设置箭头方向：
@property (nonatomic, readonly) UIPopoverArrowDirection popoverArrowDirection
3.设置内容大小：
@property (nonatomic) CGSize popoverContentSize
备注：
<1>.如果从一个导航按钮处呈现，使用：
presentPopoverFromBarButtonItem:permittedArrowDirections:animated:；
如果要从一个视图出呈现，使用：
presentPopoverFromRect:inView:permittedArrowDirections:animated:
<2>.如果设备旋转以后，位置定位错误需要在父视图控制器的下面方法里面重新定位：
didRotateFromInterfaceOrientation:（在这个方法体里面重新设置rect）
然后再次调用：
- (void)presentPopoverFromRect:(CGRect)rect inView:(UIView *)view permittedArrowDirections:(UIPopoverArrowDirection)arrowDirections animated:(BOOL)animated
例子：
TodoViewController *contentViewController = [[TodoViewController alloc] init];
UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:contentViewController];
navigationController.contentSizeForViewInPopover = CGSizeMake(100, 100); //内容大小

    UIPopoverController *popover = [[UIPopoverController alloc] initWithContentViewController:navigationController];
popover.popoverContentSize = CGSizeMake(300, 300); //弹出窗口大小，如果屏幕画不下，会挤小的。这个值默认是320x1100

CGRect popoverRect = CGRectMake(200, 700, 10, 10);
[popover presentPopoverFromRect:popoverRect //popoverRect的中心点是用来画箭头的，如果中心点如果出了屏幕，系统会优化到窗口边缘
inView:self.view //上面的矩形坐标是以这个view为参考的
   permittedArrowDirections:UIPopoverArrowDirectionDown //箭头方向
   animated:YES];

[contentViewController release];
[navigationController release];

//最佳实践，使用哪个view做参考，就以哪个view的bounds送进去就好了，箭头自动指向这个view的中心

[3] IPAD 拖动事例(也支持鼠标)

来源: 互联网发布时间: 2014-02-18

IPAD 拖动例子(也支持鼠标)
<html>
<head>
<title>iPad Touch Test</title>
<meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=0">
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
</head>

<body>
    <div id="trace"></div>

    <div id="test">
         <div onmousemove="flip(event);" >Blue</div>

    </div>


</body>

</html>

<script language=javascript >

$.fn.draggable = function(action) {

    var offset = null;

    //touch drag
    var start = function(e) {
        var orig = e.originalEvent;
        var pos = $(this).position();
        offset = {
          x: orig.changedTouches[0].pageX - pos.left,
          y: orig.changedTouches[0].pageY - pos.top
        };
    };
    var move = function(e) {
        e.preventDefault();
        var orig = e.originalEvent;
        $(this).css({
          top: orig.changedTouches[0].pageY - offset.y,
          left: orig.changedTouches[0].pageX - offset.x
        });
    };

    // mouse drag
    o = document.getElementById($(this).attr("id"));
    o.orig_x = parseInt(o.style.left) - document.body.scrollLeft;
    o.orig_y = parseInt(o.style.top) - document.body.scrollTop;
    o.orig_index = o.style.zIndex;

    var drag = function(a)
    {
        this.style.cursor = "move";
        var d=document;
        if(!a)a=window.event;
        var x = a.clientX+d.body.scrollLeft-o.offsetLeft;
        var y = a.clientY+d.body.scrollTop-o.offsetTop;

        if(o.setCapture)
            o.setCapture();
        else if(window.captureEvents)
            window.captureEvents(Event.MOUSEMOVE|Event.MOUSEUP);

        d.onmousemove = function(a)
        {
            if(!a)a=window.event;
            o.style.left = a.clientX+document.body.scrollLeft-x;
            o.style.top = a.clientY+document.body.scrollTop-y;
            o.orig_x = parseInt(o.style.left) - document.body.scrollLeft;
            o.orig_y = parseInt(o.style.top) - document.body.scrollTop;
        }

        d.onmouseup = function()
        {
            if(o.releaseCapture)
                o.releaseCapture();
            else if(window.captureEvents)
                window.captureEvents(Event.MOUSEMOVE|Event.MOUSEUP);
            d.onmousemove = null;
            d.onmouseup = null;
            d.ondragstart = null;
            d.onselectstart = null;
            d.onselect = null;
            o.style.cursor = "normal";
            o.style.zIndex = o.orig_index;
        }
    }

    if (action == "disabled")
    {
        this.unbind("touchstart", start);
        this.unbind("touchmove", move);
        this.unbind("mousedown", drag);
        o.style.cursor = "normal";
    }
    else
    {
        this.bind("touchstart", start);
        this.bind("touchmove", move);
        this.bind("mousedown", drag);
    }

};

function flip(e)
{
    $("body").css("background","blue");
    e.stopPropagation();
}

    $("#test").draggable();

function trace(msg)
{
    $("#trace").append( "<br>" + msg) ;
}

</script>