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GD32F20x User Manual
599
define a window inside the layer. The pixel inside the window will keep its original value, while
the pixel outside will be replaced with a default pixel defined in TLI_LxDC register.
The blending units first blends Layer0 and BG Layer into a temporary layer, and then blends
Layer1 and the temporary layer into destination layer. BG Layer
’s ARGB value is defined
TLI_BGC register. If a layer is disabled, blending function uses the layer
’s default color.
Figure 23-3. Block diagram of Blending
BG Layer
Layer0
Temporary
Layer
Layer1
+
Destination Layer
Blending formula
The general blending formula is:
s
C
BF
C
BF
BC
2
1
(23-1)
BC
is blended color
1
BF
is alpha calculation Factor 1 of Blending Method
C
is Current layer color
2
BF
is alpha calculation Factor 2 of Blending Method
s
C
is subjacent layers blended color
The blend factor of current pixel is either normalization Pixel Alpha x normalization Specified
Alpha or normalization Specified Alpha which is decided by register configuration.
23.5.5.
Layer configuration reload
As is described above, each layer has its own frame buffer, pixel format, window, default color
configuration registers and each register has a shadow register. A shadow register shares
the same address with the real register. Each time when the application writes to a layer-
related register address, the corresponding shadow registers is updated immediately, while
the real register will not change until a reload operation and only the real register has effect
to the TLI function.
There are two methods for application to trigger a reload operation: request reload and frame
blank reload. For request reload mode, then TLI begins to load the shadow registers into real
registers immediately after application set RQR bit in TLI_RL register. For frame blank reload
mode, after application set FBR bit in TLI_RL register, the TLI waits for a frame vertical
Summary of Contents for GD32F20 Series
Page 191: ...GD32F20x User Manual 191 Bits Fields Descriptions 31 0 TRNDATA 31 0 32 Bit Random data ...
Page 290: ...GD32F20x User Manual 290 conversion is ongoing ...
Page 325: ...GD32F20x User Manual 325 15 0 ALRM 15 0 RTC alarm value low ...
Page 385: ...GD32F20x User Manual 385 ...
Page 523: ...GD32F20x User Manual 523 clears AERR bit by writing 0 to it ...