Gradients, including drop shadows, all show up as solid blocks when I view my document on an Android phone. I tried different PDF compression and compatibility settings in an attempt to flatten and rasterize all the graphics, but it's clearly not working, as the Android viewer still identifies the outlines of transparent shapes instead of the blended pixels.

Is there any way to truly flatten these PDF graphics, so that it doesn't matter whether a PDF viewer supports transparency, while keeping the text as text?