18
edits
Changes
clarify that disposal happens to the output buffer before rendering the next frame
`y_offset` + `height` <= `IHDR` height
The `delay_num` and `delay_den` parameters together specify a fraction indicating the delay after displaying the current frame, in seconds. If the denominator is 0, it is to be treated as if it were 100 (that is, `delay_num` then specifies 1/100ths of a second). If the the value of the numerator is 0 the decoder should render the next frame as quickly as possible, though viewers may impose a reasonable lower bound on the delay. `dispose_op` specifies how the output buffer should be changed at the end of the delay (before rendering the next frame).
Valid values for `dispose_op` are:
2 APNG_DISPOSE_OP_PREVIOUS
* APNG_DISPOSE_OP_NONE: no disposal is done on this frame before rendering the next; its the contents are left on of the output bufferare left as is.* APNG_DISPOSE_OP_BACKGROUND: the frame's region of the output buffer is to be cleared to fully transparent blackbefore rendering the next frame.* APNG_DISPOSE_OP_PREVIOUS: the frame's region of the output buffer is to be reverted to the previous contentsbefore rendering the next frame.
`blend_op` specifies whether the frame is to be alpha blended into the current output buffer content, or whether it should completely replace its region in the output buffer.
