Adding an X and Y offset to the current crop effect (large refactor)

[jonoomph]

Adding an X and Y offset to the current crop effect, to better support previous clip crop parameters (for migrating crop options from OpenShot 2.5.1 to OpenShot 2.6). Also refactoring the crop effect, to actually copy the pixels into a new image buffer.

Below are my notes I used to come up with this logic (for anyone curious what kind of mental juggling is required for this):

0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10


1) Apply the bounds (DEST start + length)
   DEST START == SRC START
   LENGTH == CROPPED-WIDTH

    2 3 4 5 6 7 8 
    2 3 4 5 6 7 8 
    2 3 4 5 6 7 8 
    2 3 4 5 6 7 8 


2A) x_offset > 0 = 2
   CHANGE SRC-START += 2 = 4
   CHANGE LENGTH
     IF WIDTH - SRC-START > CROPPED-WIDTH
     IF 11 - 4 => 7
         LENGTH = CROPPED-WIDTH = 7
     ELSE
         LENGTH = WIDTH - SRC-START

    4 5 6 7 8 9 10 
    4 5 6 7 8 9 10
    4 5 6 7 8 9 10
    4 5 6 7 8 9 10


2B) x_offset > 0 = 4
   CHANGE SRC-START += 4 = 6
   CHANGE LENGTH
     IF WIDTH - SRC-START > CROPPED-WIDTH
     IF 11 - 6 => 7
         LENGTH = CROPPED-WIDTH = 7
     ELSE
         LENGTH = WIDTH - SRC-START = 11 - 6 = 5

    6 7 8 9 10 - - 
    6 7 8 9 10 - -
    6 7 8 9 10 - -
    6 7 8 9 10 - -
                        

2C) x_offset > 0
   CHANGE SRC-START = 6
   CHANGE LENGTH
     LENGTH = WIDTH - SRC START
     LENGTH = 11 - 6 = 5
        MAX-LENGTH IS CROPPED-WIDTH = 7

    6 7 8 9 10 - - 
    6 7 8 9 10 - -
    6 7 8 9 10 - -
    6 7 8 9 10 - -
       
                        
3A) x_offset < 0 = -1
   CHANGE SRC START += -1   (from 2 to 1)
     IF SRC-START < 0:
	...
     ELSE
	SRC-START = 1
	LENGTH = CROPPED-WIDTH = 7
    MAX-LENGTH IS CROPPED-WIDTH = 7

    1 2 3 4 5 6 7 
    1 2 3 4 5 6 7 
    1 2 3 4 5 6 7 
    1 2 3 4 5 6 7 
    
    
3B) x_offset < 0 = -4
   CHANGE SRC START += -4   (from 2 to -2)
     IF SRC-START < 0:
        DIFF = abs(SRC-START) = 2
	SRC-START = 0
	DEST-START += DIFF = 2 + abs(-2) = 4
	LENGTH = CROPPED-WIDTH - DIFF = 7 - 2 = 5
     ELSE
	...
    MAX-LENGTH IS CROPPED-WIDTH = 7

    - - 0 1 2 3 4 
    - - 0 1 2 3 4
    - - 0 1 2 3 4
    - - 0 1 2 3 4

[codecov]

Codecov Report

Merging #724 (5f91ddc) into develop (d58febf) will decrease coverage by 0.07%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           develop     #724      +/-   ##
===========================================
- Coverage    46.24%   46.16%   -0.08%     
===========================================
  Files          182      182              
  Lines        16725    16753      +28     
===========================================
  Hits          7734     7734              
- Misses        8991     9019      +28     

Impacted Files	Coverage Δ
src/effects/Crop.cpp	0.92% <0.00%> (-0.33%)	⬇️
src/effects/Crop.h	0.00% <ø> (ø)

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