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105 lines
3.9 KiB
105 lines
3.9 KiB
/**
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* Copyright (c) 2015-present, Horcrux.
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* All rights reserved.
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*
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* This source code is licensed under the MIT-style license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#import "RNSVGViewBox.h"
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#import <math.h>
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#import "RNSVGUse.h"
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@implementation RNSVGViewBox
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+ (CGAffineTransform)getTransform:(CGRect)vbRect
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eRect:(CGRect)eRect
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align:(NSString *)align
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meetOrSlice:(RNSVGVBMOS)meetOrSlice
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{
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// based on https://svgwg.org/svg2-draft/coords.html#ComputingAViewportsTransform
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// Let vb-x, vb-y, vb-width, vb-height be the min-x, min-y, width and height values of the viewBox attribute
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// respectively.
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CGFloat vbX = CGRectGetMinX(vbRect);
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CGFloat vbY = CGRectGetMinY(vbRect);
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CGFloat vbWidth = CGRectGetWidth(vbRect);
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CGFloat vbHeight = CGRectGetHeight(vbRect);
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// Let e-x, e-y, e-width, e-height be the position and size of the element respectively.
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CGFloat eX = CGRectGetMinX(eRect);
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CGFloat eY = CGRectGetMinY(eRect);
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CGFloat eWidth = CGRectGetWidth(eRect);
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CGFloat eHeight = CGRectGetHeight(eRect);
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// Let align be the align value of preserveAspectRatio, or 'xMidyMid' if preserveAspectRatio is not defined.
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// Let meetOrSlice be the meetOrSlice value of preserveAspectRatio, or 'meet' if preserveAspectRatio is not defined or
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// if meetOrSlice is missing from this value.
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// Initialize scale-x to e-width/vb-width.
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CGFloat scaleX = eWidth / vbWidth;
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// Initialize scale-y to e-height/vb-height.
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CGFloat scaleY = eHeight / vbHeight;
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// Initialize translate-x to e-x - (vb-x * scale-x).
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// Initialize translate-y to e-y - (vb-y * scale-y).
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CGFloat translateX = eX - (vbX * scaleX);
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CGFloat translateY = eY - (vbY * scaleY);
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// If align is 'none'
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if (meetOrSlice == kRNSVGVBMOSNone) {
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// Let scale be set the smaller value of scale-x and scale-y.
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// Assign scale-x and scale-y to scale.
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CGFloat scale = scaleX = scaleY = fmin(scaleX, scaleY);
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// If scale is greater than 1
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if (scale > 1) {
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// Minus translateX by (eWidth / scale - vbWidth) / 2
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// Minus translateY by (eHeight / scale - vbHeight) / 2
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translateX -= (eWidth / scale - vbWidth) / 2;
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translateY -= (eHeight / scale - vbHeight) / 2;
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} else {
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translateX -= (eWidth - vbWidth * scale) / 2;
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translateY -= (eHeight - vbHeight * scale) / 2;
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}
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} else {
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// If align is not 'none' and meetOrSlice is 'meet', set the larger of scale-x and scale-y to the smaller.
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// Otherwise, if align is not 'none' and meetOrSlice is 'slice', set the smaller of scale-x and scale-y to the
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// larger.
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if (![align isEqualToString:@"none"] && meetOrSlice == kRNSVGVBMOSMeet) {
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scaleX = scaleY = fmin(scaleX, scaleY);
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} else if (![align isEqualToString:@"none"] && meetOrSlice == kRNSVGVBMOSSlice) {
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scaleX = scaleY = fmax(scaleX, scaleY);
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}
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// If align contains 'xMid', add (e-width - vb-width * scale-x) / 2 to translate-x.
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if ([align containsString:@"xMid"]) {
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translateX += (eWidth - vbWidth * scaleX) / 2.0;
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}
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// If align contains 'xMax', add (e-width - vb-width * scale-x) to translate-x.
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if ([align containsString:@"xMax"]) {
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translateX += (eWidth - vbWidth * scaleX);
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}
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// If align contains 'yMid', add (e-height - vb-height * scale-y) / 2 to translate-y.
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if ([align containsString:@"YMid"]) {
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translateY += (eHeight - vbHeight * scaleY) / 2.0;
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}
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// If align contains 'yMax', add (e-height - vb-height * scale-y) to translate-y.
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if ([align containsString:@"YMax"]) {
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translateY += (eHeight - vbHeight * scaleY);
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}
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}
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// The transform applied to content contained by the element is given by
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// translate(translate-x, translate-y) scale(scale-x, scale-y).
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CGAffineTransform transform = CGAffineTransformMakeTranslation(translateX, translateY);
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return CGAffineTransformScale(transform, scaleX, scaleY);
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}
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@end
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