android - 基于 ppi 的像素到 dp 转换器

Question

我正在将给定图形的 px 转换为 dp。通过文档我注意到 1dp = 3px 用于 480ppi 屏幕（xxhdpi）。

我在 Redmi Note3 上对其进行测试，它的 ppi 约为 403。

我的设计师为我提供了以像素为单位的边距。我应该使用 1:3 比例将它们转换为像素还是应该不同

Answer 1

/**
 * This method converts dp unit to equivalent pixels, depending on device density. 
 * 
 * @param dp A value in dp (density independent pixels) unit. Which we need to convert into pixels
 * @param context Context to get resources and device specific display metrics
 * @return A float value to represent px equivalent to dp depending on device density
 */
public static float convertDpToPixel(float dp, Context context){
    Resources resources = context.getResources();
    DisplayMetrics metrics = resources.getDisplayMetrics();
    float px = dp * ((float)metrics.densityDpi / DisplayMetrics.DENSITY_DEFAULT);
    return px;
}

/**
 * This method converts device specific pixels to density independent pixels.
 * 
 * @param px A value in px (pixels) unit. Which we need to convert into db
 * @param context Context to get resources and device specific display metrics
 * @return A float value to represent dp equivalent to px value
 */
public static float convertPixelsToDp(float px, Context context){
    Resources resources = context.getResources();
    DisplayMetrics metrics = resources.getDisplayMetrics();
    float dp = px / ((float)metrics.densityDpi / DisplayMetrics.DENSITY_DEFAULT);
    return dp;
}

有关更多信息，请查看此 SOF 帖子将像素转换为 dp