Gradient fill color Algorithm

Method 1:
Bilinear interpolation method

1. Calculate the zoom ratio first. Bl = 2/W... 2 is the source image width (because there are only two colors)... W is the enlarged width.
2. Start the loop, from 1 to w the target width. If the loop variable is I..., use n = I * BL.
3. extract the fractional part of N and store it in Variable P .. then synthesize the color. The target color r = R1 * (1-p) + R2 * p g = G1 * (1-p) + G2 * p B = b1 * (1-p) + B2 * p .... r1/G1/B1 is the starting color of red/green/blue, R2/G2/B2 is the ending color of red/green/blue.

 

Color g_color [3] = {255, 0, 0,255}, {0,255, 0,255}, {0, 0,255,255 }};
U8 g_perc [2] = {30, 70 };
Gradient_color g_gc = {g_color, g_perc, 3 };

Void fill_gradient_color (s32 X1, s32 Y1, s32 X2, s32 Y2)
{
S32 I;
S32 done = 0;
S32 W;
S32 P;
S32 fill_width;
S32 x_start = 0, x_end;
S32 X;
Float BL;
Float n, m;
Float TR, TG, TB;
Color start_color, end_color, C;
 
Gradient_color * GC = & g_gc;

Fill_width = x2-x1;
 
For (I = 0; (I <(GC-> n-1 )&&! Done); I ++)
{
Start_color = GC-> C [I];
End_color = GC-> C [I + 1];
P = GC-> P [I];
X_end = x_start + pixtel_percent (fill_width, P );
If (x_end> fill_width-1)
{
X_end = fill_width-1;
Done = 1;
}

W = x_end-x_start;
BL = 1.0/(float) W;

C. R = start_color.r;
C. G = start_color.g;
C. B = start_color. B;
C. Alpha = start_color.alpha;
For (x = 1; x <= W; X ++)
{
S32 TMP;
N = (float) x * BL;
TMP = (s32) N;
M = N-(float) TMP;
Gui_draw_vertical_line (Y1, Y2, X1 + x_start + X, C );

Tr = start_color.r * (1.0-m) + end_color.r * m;
Tg = start_color.g * (1.0-m) + end_color.g * m;
TB = start_color. B * (1.0-m) + end_color. B * m;
C. R = (s8) TR;
C. G = (s8) TG;
C. B = (s8) TB;
}
X_start = x_end-1;
}
}

 

 

Method 2:
Divisor is the gradient width, IR, Ig, IB is the incremental value of different color components, IR = (R2-R1)/divisor, Ig = (G2-G1)/divisor, IB = (B2-B1)/divisor, R1/G1/B1 is the starting color of red/green/blue, R2/G2/B2 is the ending color of red/green/blue. then, starting from the initial color value, each painting increases the color value components by IR, Ig, and IB.

For (I = 0; (I <(GC-> n-1 )&&! Done); I ++)
{
Start_color = GC-> C [I];
End_color = GC-> C [I + 1];
P = GC-> P [I];
X_end = x_start + pixtel_percent (fill_width, P );
If (x_end> fill_width-1)
{
X_end = fill_width-1;
Done = 1;
}
Divisor = (float) (x_end-x_start) + 1;
If (divisor = 0)
{
Divisor = 1;
}
IR =-(start_color.r-end_color.r)/divisor;
IG =-(start_color.g-end_color.g)/divisor;
IB =-(start_color. B-end_color. B)/divisor;
Tr = C. R = start_color.r;
Tg = c. g = start_color.g;
TB = C. B = start_color. B;
C. Alpha = start_color.alpha;
For (x = x_start; x <= x_end; X ++)
{
Gui_draw_vertical_line (Y1, Y2, x + X1, C );
Tr + = IR;
Tg + = ig;
TB + = Ib;
C. R = (s8) TR;
C. G = (s8) TG;
C. B = (s8) TB;
}
X_start = x_end + 1;
}