我要评论本文实例为大家分享了c# picturebox实现图像拖拽和缩放的具体代码，供大家参考，具体内容如下
1.核心步骤：
①新建point类型全局变量mousedownpoint，记录拖拽过程中鼠标位置；
②mousedown事件记录cursor位置；
③mousemove事件计算移动矢量，并更新picturebox1.location。
代码：
private void picturebox1_mousedown(object sender, mouseeventargs e)
{
if (e.button == mousebuttons.left)
{
mousedownpoint.x = cursor.position.x; //记录鼠标左键按下时位置
mousedownpoint.y = cursor.position.y;
ismove = true;
picturebox1.focus(); //鼠标滚轮事件(缩放时)需要picturebox有焦点
}
}
private void picturebox1_mouseup(object sender, mouseeventargs e)
{
if (e.button == mousebuttons.left)
{
ismove = false;
}
}
private void picturebox1_mousemove(object sender, mouseeventargs e)
{
picturebox1.focus(); //鼠标在picturebox上时才有焦点，此时可以缩放
if (ismove)
{
int x, y; //新的picturebox1.location(x,y)
int movex, movey; //x方向，y方向移动大小。
movex = cursor.position.x - mousedownpoint.x;
movey = cursor.position.y - mousedownpoint.y;
x = picturebox1.location.x + movex;
y = picturebox1.location.y + movey;
picturebox1.location = new point(x, y);
mousedownpoint.x = cursor.position.x;
mousedownpoint.y = cursor.position.y;
}
}
private void panel2_mousedown(object sender, mouseeventargs e)
{
if (e.button == mousebuttons.left)
{
mousedownpoint.x = cursor.position.x; //记录鼠标左键按下时位置
mousedownpoint.y = cursor.position.y;
ismove = true;
}
}
private void panel2_mouseup(object sender, mouseeventargs e)
{
if (e.button == mousebuttons.left)
{
ismove = false;
}
}
private void panel2_mousemove(object sender, mouseeventargs e)
{
panel2.focus(); //鼠标不在picturebox上时焦点给别的控件，此时无法缩放
if (ismove)
{
int x, y; //新的picturebox1.location(x,y)
int movex, movey; //x方向，y方向移动大小。
movex = cursor.position.x - mousedownpoint.x;
movey = cursor.position.y - mousedownpoint.y;
x = picturebox1.location.x + movex;
y = picturebox1.location.y + movey;
picturebox1.location = new point(x, y);
mousedownpoint.x = cursor.position.x;
mousedownpoint.y = cursor.position.y;
}
}
2.图像缩放
核心思想：利用picturebox的zoom模式，根据图像显示大小更改picturebox大小，记录鼠标位置补偿缩放位移，实现锚点缩放，即以鼠标位置为中心进行缩放。
zoomstep --- 自己定义滚轮滑动缩放大小
代码：
//实现锚点缩放(以鼠标所指位置为中心缩放)；
//步骤：
//①先改picturebox长宽，长宽改变量一样；
//②获取缩放后picturebox中实际显示图像的长宽，这里长宽是不一样的；
//③将picturebox的长宽设置为显示图像的长宽；
//④补偿picturebox因缩放产生的位移，实现锚点缩放。
// 注释：为啥要②③步？由于zoom模式的机制，把picturebox背景设为黑就知道为啥了。
//这里需要获取zoom模式下picturebox所显示图像的大小信息，添加 using system.reflection；
//picturebox1_mousewheel事件没找到。。。手动添加，别忘在form1.designer.cs的“windows 窗体设计器生成的代码”里加入：
//this.picturebox1.mousewheel += new system.windows.forms.mouseeventhandler(this.picturebox1_mousewheel)。
private void picturebox1_mousewheel(object sender, mouseeventargs e)
{
int x = e.location.x;
int y = e.location.y;
int ow = picturebox1.width;
int oh = picturebox1.height;
int vx, vy; //因缩放产生的位移矢量
if (e.delta > 0) //放大
{
//第①步
picturebox1.width += zoomstep;
picturebox1.height += zoomstep;
//第②步
propertyinfo pinfo = picturebox1.gettype().getproperty("imagerectangle", bindingflags.instance |
bindingflags.nonpublic);
rectangle rect = (rectangle)pinfo.getvalue(picturebox1, null);
//第③步
picturebox1.width = rect.width;
picturebox1.height = rect.height;
}
if (e.delta < 0) //缩小
{
//防止一直缩成负值
if (picturebox1.width < mybmp.width / 10)
return;
picturebox1.width -= zoomstep;
picturebox1.height -= zoomstep;
propertyinfo pinfo = picturebox1.gettype().getproperty("imagerectangle", bindingflags.instance |
bindingflags.nonpublic);
rectangle rect = (rectangle)pinfo.getvalue(picturebox1, null);
picturebox1.width = rect.width;
picturebox1.height = rect.height;
}
//第④步，求因缩放产生的位移，进行补偿，实现锚点缩放的效果
vx = (int)((double)x * (ow - picturebox1.width) / ow);
vy = (int)((double)y * (oh - picturebox1.height) / oh);
picturebox1.location = new point(picturebox1.location.x + vx, picturebox1.location.y + vy);
}
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持移动技术网。
您可能感兴趣的文章:
如您对本文有疑问或者有任何想说的，请点击进行留言回复，万千网友为您解惑！
网友评论