colorramp: Use supplied gamma ramps as initial value

This changes colorramp_fill() to base the ramp calculations on the
existing values in the supplied tables, instead of basing it on a pure
`i/size` value computed on the fly.

All gamma adjustment methods are changed to explicitly initialize the ramps
to the `i/size` value before calls to colorramp_fill().

1 files changed, 8 insertions, 0 deletions

diff --git a/src/gamma-randr.c b/src/gamma-randr.c
index 4f6b0f0..5ef7a4f 100644
--- a/src/gamma-randr.c
+++ b/src/gamma-randr.c
@@ -327,6 +327,14 @@ randr_set_temperature_for_crtc(randr_state_t *state, int crtc_num,
 	uint16_t *gamma_g = &gamma_ramps[1*ramp_size];
 	uint16_t *gamma_b = &gamma_ramps[2*ramp_size];
 
+	/* Initialize gamma ramps to pure state */
+	for (int i = 0; i < ramp_size; i++) {
+		uint16_t value = (double)i/ramp_size * (UINT16_MAX+1);
+		gamma_r[i] = value;
+		gamma_g[i] = value;
+		gamma_b[i] = value;
+	}
+
 	colorramp_fill(gamma_r, gamma_g, gamma_b, ramp_size,
 		       setting);