android屏幕单位转换

最新推荐文章于 2021-05-26 09:42:16 发布

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最新推荐文章于 2021-05-26 09:42:16 发布

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本文介绍如何在Android应用中使用TypedValue.applyDimension函数进行单位转换，以及如何通过MySystemParams类获取设备屏幕的宽度、高度、dpi密度、横竖屏状态等参数。

在android内部会使用TypedValue.applyDimension函数将所有单位换算成px。

public static float applyDimension(int unit, float value,
                                   DisplayMetrics metrics)
{
    switch (unit) {
    case COMPLEX_UNIT_PX:
        return value;
    case COMPLEX_UNIT_DIP:
        return value * metrics.density;
    case COMPLEX_UNIT_SP:
        return value * metrics.scaledDensity;
    case COMPLEX_UNIT_PT:
        return value * metrics.xdpi * (1.0f/72);
    case COMPLEX_UNIT_IN:
        return value * metrics.xdpi;
    case COMPLEX_UNIT_MM:
        return value * metrics.xdpi * (1.0f/25.4f);
    }
    return 0;
}

public static float applyDimension(int unit, float value,DisplayMetrics metrics)

Since: API Level 1

Converts an unpacked complex data value holding a dimension to its final floating point value. The two parametersunit andvalue are as in TYPE_DIMENSION.

Parameters

unit	The unit to convert from.
value	The value to apply the unit to.
metrics	Current display metrics to use in the conversion -- supplies display density and scaling information.

Returns

The complex floating point value multiplied by the appropriate metrics depending on its unit.

/**
 * Android大小单位转换工具类
 * 
 * @author wader
 * 
 */
public class DisplayUtil {
 /**
  * 将px值转换为dip或dp值，保证尺寸大小不变
  * 
  * @param pxValue
  * @param scale（DisplayMetrics类中属性density）
  * @return
  */
 public static int px2dip(float pxValue, float scale) {
  return (int) (pxValue / scale + 0.5f);
 }

 /**
  * 将dip或dp值转换为px值，保证尺寸大小不变
  * 
  * @param dipValue
  * @param scale（DisplayMetrics类中属性density）
  * @return
  */
 public static int dip2px(float dipValue, float scale) {
  return (int) (dipValue * scale + 0.5f);
 }

 /**
  * 将px值转换为sp值，保证文字大小不变
  * 
  * @param pxValue
  * @param fontScale（DisplayMetrics类中属性scaledDensity）
  * @return
  */
 public static int px2sp(float pxValue, float fontScale) {
  return (int) (pxValue / fontScale + 0.5f);
 }

 /**
  * 将sp值转换为px值，保证文字大小不变
  * 
  * @param spValue
  * @param fontScale（DisplayMetrics类中属性scaledDensity）
  * @return
  */
 public static int sp2px(float spValue, float fontScale) {
  return (int) (spValue * fontScale + 0.5f);
 }
}

获取Android设备屏幕宽、高、dpi密度及横竖屏等参数

/**
 * 系统参数类
 * 
 * @author wader
 * 
 */
public class MySystemParams {
 private final String TAG = "SystemParams";
 private static MySystemParams params;
 public int screenWidth;// 屏幕宽度，单位为px
 public int screenHeight;// 屏幕高度，单位为px
 public int densityDpi;// 屏幕密度，单位为dpi
 public float scale;// 缩放系数，值为 densityDpi/160
 public float fontScale;// 文字缩放系数，同scale
 
 public final static int SCREEN_ORIENTATION_VERTICAL = 1; // 屏幕状态：横屏
 public final static int SCREEN_ORIENTATION_HORIZONTAL = 2; // 屏幕状态：竖屏
 public int screenOrientation = SCREEN_ORIENTATION_VERTICAL;// 当前屏幕状态，默认为竖屏
 
 /**
  * 私有构造方法
  * 
  * @param activity
  */
 private MySystemParams(Activity activity) {
  DisplayMetrics dm = new DisplayMetrics();
  activity.getWindowManager().getDefaultDisplay().getMetrics(dm);
  screenWidth = dm.widthPixels;
  screenHeight = dm.heightPixels;
  densityDpi = dm.densityDpi;
  scale = dm.density;
  fontScale = dm.scaledDensity;
 
  screenOrientation = screenHeight > screenWidth ? SCREEN_ORIENTATION_VERTICAL
    : SCREEN_ORIENTATION_HORIZONTAL;
 }
 
 /**
  * 获取实例
  * 
  * @param activity
  * @return
  */
 public static MySystemParams getInstance(Activity activity) {
  if (params == null) {
   params = new MySystemParams(activity);
  }
  return params;
 }
 
 /**
  * 获取一个新实例
  * 
  * @param activity
  * @return
  */
 public static MySystemParams getNewInstance(Activity activity) {
  if (params != null) {
   params = null;
  }
  return getInstance(activity);
 }
 
 /**
  * 参数信息
  */
 public String toString() {
 
  return TAG
    + ":[screenWidth: "
    + screenWidth
    + " screenHeight: "
    + screenHeight
    + " scale: "
    + scale
    + " fontScale: "
    + fontScale
    + " densityDpi: "
    + densityDpi
    + " screenOrientation: "
    + (screenOrientation == SCREEN_ORIENTATION_VERTICAL ? "vertical"
      : "horizontal") + "]";
 }
}

转至http://www.cnblogs.com/zhouchanwen/archive/2012/10/20/2731984.html