android - Conversion of dp to px and px to dp. Conceptual misunderstanding.

Question

I am a bit confused regarding the conversion of dp to px and px to dp. The formula goes this way

px = dp*(dpi/160)

Let's consider two screens A & B of densities of 160 dpi and 320 dpi respectively. This itself means that in the same area B has more number of pixels than A which means the pixel size of 160dpi screen should be larger for the same screen size and should be equal to the physical size of 2 pixels of 320dpi screen. But, putting in the formula for B this gives that 1 pixel for B is equivalent to the physical size of 2 density independent pixels or 2 pixels of 160dpi screen. What am I missing here?

标签： androidandroid-layout

Answer 1

尝试通过此示例了解缩放系统。假设您有一个要在每个屏幕上显示48dp x 48dp大的位图（与密度无关）。我们有：

• mDPI，160dpi 屏幕（比率1x）--> 位图：48x48 px（旧设备）
• hDPI，240dpi 屏幕（比例1.5x）--> 位图：72x72 px (48 x 1.5)
• xhDPI，320dpi 屏幕（比率2x）--> 位图：96x96 像素（48 x 2）
• xxhDPI，480dpi 屏幕（比例3x）--> 位图：144x144 像素（48 x 3）
• xxxhDPI，640dpi 屏幕（比例4x）--> 位图：192x192 px (48 x 4)

简而言之，要回答您的问题，不同密度的像素数量不同，但dps数量相同。