CoderHenry66 · beforeold · Sep 15, 2019
diff --git a/WAVideoBox.xcodeproj/project.pbxproj b/WAVideoBox.xcodeproj/project.pbxproj
@@ -34,6 +34,7 @@
 		3B90283821E1FF22001B1497 /* nature.mp4 in Resources */ = {isa = PBXBuildFile; fileRef = 3B90283321E1FF22001B1497 /* nature.mp4 */; };
 		3BCAF55621E72B8000663097 /* test2.mp4 in Resources */ = {isa = PBXBuildFile; fileRef = 3BCAF55521E72B8000663097 /* test2.mp4 */; };
 		3BD923AA21E44D8F007D85B8 /* test1.mp4 in Resources */ = {isa = PBXBuildFile; fileRef = 3BD923A921E44D8F007D85B8 /* test1.mp4 */; };
+		E43E6F47232E27BB0025C062 /* WAAVSECropCommand.m in Sources */ = {isa = PBXBuildFile; fileRef = E43E6F46232E27BA0025C062 /* WAAVSECropCommand.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -103,6 +104,8 @@
 		3B90283321E1FF22001B1497 /* nature.mp4 */ = {isa = PBXFileReference; lastKnownFileType = file; path = nature.mp4; sourceTree = "<group>"; };
 		3BCAF55521E72B8000663097 /* test2.mp4 */ = {isa = PBXFileReference; lastKnownFileType = file; path = test2.mp4; sourceTree = "<group>"; };
 		3BD923A921E44D8F007D85B8 /* test1.mp4 */ = {isa = PBXFileReference; lastKnownFileType = file; path = test1.mp4; sourceTree = "<group>"; };
+		E43E6F45232E27BA0025C062 /* WAAVSECropCommand.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = WAAVSECropCommand.h; sourceTree = "<group>"; };
+		E43E6F46232E27BA0025C062 /* WAAVSECropCommand.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = WAAVSECropCommand.m; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -201,6 +204,8 @@
 		3B9027FF21E1F2F3001B1497 /* WAAVSeCommand */ = {
 			isa = PBXGroup;
 			children = (
+				E43E6F45232E27BA0025C062 /* WAAVSECropCommand.h */,
+				E43E6F46232E27BA0025C062 /* WAAVSECropCommand.m */,
 				3B90280A21E1F2F3001B1497 /* WAAVSEComposition.h */,
 				3B90281521E1F2F3001B1497 /* WAAVSEComposition.m */,
 				3B90280221E1F2F3001B1497 /* WAAVSECommand.h */,
@@ -387,6 +392,7 @@
 				3B222FF921E863DC0056CE83 /* WAAVSEExtractSoundCommand.m in Sources */,
 				3B90282121E1F2F3001B1497 /* WAAVSEReplaceSoundCommand.m in Sources */,
 				3B9027DB21E1F2E9001B1497 /* main.m in Sources */,
+				E43E6F47232E27BB0025C062 /* WAAVSECropCommand.m in Sources */,
 				3B90281B21E1F2F3001B1497 /* WAAVSEGearboxCommand.m in Sources */,
 				3B90281D21E1F2F3001B1497 /* WAAVSERotateCommand.m in Sources */,
 				3B9027CD21E1F2E7001B1497 /* AppDelegate.m in Sources */,

diff --git a/WAVideoBox/WAVideoBox/WAAVSeCommand/WAAVSECropCommand.h b/WAVideoBox/WAVideoBox/WAAVSeCommand/WAAVSECropCommand.h
@@ -0,0 +1,21 @@
+//   
+//   WAAVSECropCommand.h
+//   WAVideoBox
+//   
+//   Created  by Hallfry on 2019/4/17
+//   Modified by Hallfry
+//   Copyright © 2019年 XPLO. All rights reserved.
+//   区域裁剪
+
+
+#import "WAAVSECommand.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface WAAVSECropCommand : WAAVSECommand
+
+- (void)performWithAsset:(AVAsset *)asset cropRect:(CGRect)cropRect;
+
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/WAVideoBox/WAVideoBox/WAAVSeCommand/WAAVSECropCommand.m b/WAVideoBox/WAVideoBox/WAAVSeCommand/WAAVSECropCommand.m
@@ -0,0 +1,84 @@
+//   
+//   WAAVSECropCommand.m
+//   WAVideoBox
+//   
+//   Created  by Hallfry on 2019/4/17
+//   Modified by Hallfry
+//   Copyright © 2019年 XPLO. All rights reserved.
+//   
+
+
+#import "WAAVSECropCommand.h"
+
+
+@interface AVAssetTrack(XPAssetTrack)
+
+- (CGAffineTransform)getTransformWithCropRect:(CGRect)cropRect;
+
+@end
+
+@implementation AVAssetTrack(XPAssetTrack)
+- (CGAffineTransform)getTransformWithCropRect:(CGRect)cropRect {
+
+    CGSize renderSize = cropRect.size;
+    CGFloat renderScale = renderSize.width / cropRect.size.width;
+    CGPoint offset = CGPointMake(-cropRect.origin.x, -cropRect.origin.y);
+    double rotation = atan2(self.preferredTransform.b, self.preferredTransform.a);
+
+    CGPoint rotationOffset = CGPointMake(0, 0);
+    if (self.preferredTransform.b == -1.0) { // 倒着拍 -M_PI_2
+        rotationOffset.y = self.naturalSize.width;
+    } else if (self.preferredTransform.c == -1.0) { // 正着拍 M_PI_2
+        // 奇怪的偏移
+        rotationOffset.x = self.naturalSize.height;
+    } else if (self.preferredTransform.a == -1.0) { // 两侧拍 M_PI
+        rotationOffset.x = self.naturalSize.width;
+        rotationOffset.y = self.naturalSize.height;
+    }
+
+    CGAffineTransform transform = CGAffineTransformIdentity;
+    transform = CGAffineTransformScale(transform, renderScale, renderScale);
+    transform = CGAffineTransformTranslate(transform, offset.x + rotationOffset.x, offset.y + rotationOffset.y);
+    transform = CGAffineTransformRotate(transform, rotation);
+
+    return transform;
+}
+
+@end
+
+
+@implementation WAAVSECropCommand
+
+- (void)performWithAsset:(AVAsset *)asset cropRect:(CGRect)cropRect {
+    [super performWithAsset:asset];
+
+    if ([[self.composition.mutableComposition tracksWithMediaType:AVMediaTypeVideo] count] != 0) {
+
+        [super performVideoCompopsition];
+
+        // 绿边问题，是因为宽或高不是偶数
+        int64_t renderWidth = round(cropRect.size.width);
+        int64_t renderHeight = round(cropRect.size.height);
+        if (renderWidth % 2 != 0) {
+            renderWidth -= 1;
+        }
+        if (renderHeight % 2 != 0) {
+            renderHeight -= 1;
+        }
+
+        AVMutableVideoCompositionInstruction *instruction = [self.composition.instructions lastObject];
+        AVMutableVideoCompositionLayerInstruction *layerInstruction = (AVMutableVideoCompositionLayerInstruction *)instruction.layerInstructions[0];
+
+        // 获取父类的属性进行方向矫正
+        // 更安全的话，可以考虑让父类暴露属性
+        AVAssetTrack *videoTrack = [self valueForKey:@"assetVideoTrack"];
+
+        [layerInstruction setTransform:[videoTrack getTransformWithCropRect:cropRect] atTime:kCMTimeZero];
+        [layerInstruction setOpacity:1.0 atTime:kCMTimeZero];
+
+
+        self.composition.mutableVideoComposition.renderSize = CGSizeMake(renderWidth, renderHeight);
+    }
+}
+
+@end