Question

我正在尝试将pan和zoom添加到我在application.js中编写的应用程序，这是我的代码：

boolean surfaceTouchEvent(MotionEvent event) {
pointNum=event.getPointerCount();
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
//User is pressing on finger
float x0=event.getX(0);
float y0=event.getY(0);
mode = false; //DRAG
break;
case MotionEvent.ACTION_POINTER_DOWN:
x1=event.getX(0);x2=event.getX(1);
y1=event.getY(0);y2=event.getY(1);
float z4 = dist(x1,y1,x2,y2);
mode = true; // pinch
break;
case MotionEvent.ACTION_POINTER_UP:
// User is released one of the fingers.

break;
case MotionEvent.ACTION_MOVE:
if (mode = false){
x1=event.getX(0)-x0;
y1=event.getY(0)-y0;
}
if (mode = true){
x1=event.getX(0);x2=event.getX(1);
y1=event.getY(0);y2=event.getY(1);
float z3 = dist(x1,y1,x2,y2);
if ( z3 > z4 ){ 
zoom += 0.1;
}
else if ( z3 < z4){
zoom -= 0.1;  
}
}
break;
}
return super.surfaceTouchEvent(event);
}

我保存较旧的位置，以防止MotionEvent.ACTION_POINTER_DOWN进行缩放，如果是MotionEvent.ACTION_DOWN则进行平移。我需要这些较旧的位置来比较新距离和缩放中的旧距离，例如

这是错误：

compile:
    [javac] Compiling 2 source files to C:\DOCUME~1\T0P4568\LOCALS~1\Temp\android893850823480544580.pde\bin\classes
    [javac] C:\DOCUME~1\T0P4568\LOCALS~1\Temp\android893850823480544580.pde\src\changethispackage\beforesubmitting\tothemarket\sketch_may28a\sketch_may28a.java:118: variable x0 might not have been initialized
    [javac] x1=event.getX(0)-x0;
    [javac]                  ^
    [javac] C:\DOCUME~1\T0P4568\LOCALS~1\Temp\android893850823480544580.pde\src\changethispackage\beforesubmitting\tothemarket\sketch_may28a\sketch_may28a.java:119: variable y0 might not have been initialized
    [javac] y1=event.getY(0)-y0;
    [javac]                  ^
    [javac] C:\DOCUME~1\T0P4568\LOCALS~1\Temp\android893850823480544580.pde\src\changethispackage\beforesubmitting\tothemarket\sketch_may28a\sketch_may28a.java:125: variable z4 might not have been initialized
    [javac] if ( z3 > z4 ){
    [javac]           ^
    [javac] 3 errors

请帮忙！

Answer 1

好的，您显然正在使用processing.org，它将其代码编译为java。

解决方案很简单：将x0，y0和z4预初始化为默认值，例如0。

这只是为了安抚java编译器，它不够聪明，无法理解它们被读取的时间，它们已经被初始化了。

添加平移和缩放错误

1 个答案: