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displayio: ColorConverter: fix logic errors about transparent pixels

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The transparent_color field was never initialized.  I _think_ this means
its value was always set to 0, or the blackest of blacks.  Instead,
initialize it to the sentinel value, newly given the name
NO_TRANSPARENT_COLOR.

This exposed a second problem: The test for whether there was an existing
transparent color was wrong (backwards).  I am guessing that this was not
found due to the first bug; since the converter had a transparent color,
the correct test would have led to always getting the error "Only one
color can be transparent at a time".

Closes #3723
This commit is contained in:
Jeff Epler 2020-12-16 13:48:07 -06:00
parent f2204d7d88
commit 28bd29eb42
1 changed files with 6 additions and 3 deletions
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9
shared-module/displayio/ColorConverter.c
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@ -29,6 +29,8 @@
#include "py/misc.h"
#include "py/runtime.h"
#define NO_TRANSPARENT_COLOR (0x1000000)
uint32_t displayio_colorconverter_dither_noise_1 (uint32_t n)
{
n = (n >> 13) ^ n;
@ -42,6 +44,7 @@ uint32_t displayio_colorconverter_dither_noise_2(uint32_t x, uint32_t y) {
void common_hal_displayio_colorconverter_construct(displayio_colorconverter_t* self, bool dither) {
self->dither = dither;
self->transparent_color = NO_TRANSPARENT_COLOR;
}
uint16_t displayio_colorconverter_compute_rgb565(uint32_t color_rgb888) {
@ -130,7 +133,7 @@ bool common_hal_displayio_colorconverter_get_dither(displayio_colorconverter_t*
}
void common_hal_displayio_colorconverter_make_transparent(displayio_colorconverter_t* self, uint32_t transparent_color) {
if (self->transparent_color >= 0x1000000) {
if (self->transparent_color != NO_TRANSPARENT_COLOR) {
mp_raise_RuntimeError(translate("Only one color can be transparent at a time"));
}
self->transparent_color = transparent_color;
@ -138,8 +141,8 @@ void common_hal_displayio_colorconverter_make_transparent(displayio_colorconvert
void common_hal_displayio_colorconverter_make_opaque(displayio_colorconverter_t* self, uint32_t transparent_color) {
(void) transparent_color;
// 0x1000000 will never equal a valid color
self->transparent_color = 0x1000000;
// NO_TRANSPARENT_COLOR will never equal a valid color
self->transparent_color = NO_TRANSPARENT_COLOR;
}
void displayio_colorconverter_convert(displayio_colorconverter_t *self, const _displayio_colorspace_t* colorspace, const displayio_input_pixel_t *input_pixel, displayio_output_pixel_t *output_color) {