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  • 发布：20 分钟前
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如何解决拖拽功能和长按功能的冲突问题

分类：uts

问题现象
在List组件中，单个ListItem在同时设置拖拽功能与长按功能时，实际运行之后会产生冲突，如何解决单个ListItem拖拽功能和长按功能的冲突问题？

效果预览
点击放大

背景知识
支持统一拖拽提供了一种通过鼠标或手势触屏传递数据的机制，即从一个组件位置拖出数据并将其拖入到另一个组件位置，以触发响应。
长按手势通过长按屏幕触发长按手势事件。
由于拖拽事件和长按手势都需要通过长按来触发，因此这种组合手势类型会出现冲突，例如List组件中每个ListItem都设置单独的长按事件时，拖拽功能和长按手势功能就会出现冲突。
Grid网格容器，由“行”和“列”分割的单元格所组成，通过指定“项目”所在的单元格做出各种各样的布局。
滑动手势PanGesture，能够提供自定义拖拽事件的功能。
解决方案
由于在ListItem中设置单独的长按事件会与拖拽事件产生冲突，因此建议放弃List本身的拖拽事件，使用滑动手势PanGesture，自行实现拖拽过程的逻辑，然后再通过组合手势的功能，去实现其他的长按事件。
import curves from '@ohos.curves';

@Entry
@Component
struct Page {
// 元素数组
@State numbers: number[] = [];
// 多列
private str: string = '';
row: number = 4;
// 元素数组中最后一个元素的索引
@State lastIndex: number = 0;
@State dragItem: number = -1;
@State scaleItem: number = -1;
item: number = -1;
private dragRefOffsetX: number = 0;
private dragRefOffsetY: number = 0;
@State offsetX: number = 0;
@State offsetY: number = 0;
private FIX_VP_X: number = 108;
private FIX_VP_Y: number = 120;

aboutToAppear() {
for (let i = 1; i <= 36; i++) {
this.numbers.push(i);
}
this.lastIndex = this.numbers.length - 1;
// 多列
for (let i = 0; i < this.row; i++) {
this.str = this.str + '1fr ';
}
}

itemMove(index: number, newIndex: number): void {
console.info('index:' + index + ' newIndex:' + newIndex);
if (!this.isDraggable(newIndex)) {
return;
}
let tmp = this.numbers.splice(index, 1);
this.numbers.splice(newIndex, 0, tmp[0]);
}

// 向下滑
down(index: number): void {
if (!this.isDraggable(index + this.row)) {
return;
}
this.offsetY -= this.FIX_VP_Y;
this.dragRefOffsetY += this.FIX_VP_Y;
// 多列
this.itemMove(index, index + this.row);
}

// 向下滑(右下角为空)
down2(index: number): void {
if (!this.isDraggable(index + 3)) {
return;
}
this.offsetY -= this.FIX_VP_Y;
this.dragRefOffsetY += this.FIX_VP_Y;
this.itemMove(index, index + 3);
}

// 向上滑
up(index: number): void {
if (!this.isDraggable(index - this.row)) {
return;
}
this.offsetY += this.FIX_VP_Y;
this.dragRefOffsetY -= this.FIX_VP_Y;
this.itemMove(index, index - this.row);
}

// 向左滑
left(index: number): void {
if (!this.isDraggable(index - 1)) {
return;
}
this.offsetX += this.FIX_VP_X;
this.dragRefOffsetX -= this.FIX_VP_X;
this.itemMove(index, index - 1);
}

// 向右滑
right(index: number): void {
if (!this.isDraggable(index + 1)) {
return;
}
this.offsetX -= this.FIX_VP_X;
this.dragRefOffsetX += this.FIX_VP_X;
this.itemMove(index, index + 1);
}

// 向右下滑
lowerRight(index: number): void {
if (!this.isDraggable(index + this.row + 1)) {
return;
}
this.offsetX -= this.FIX_VP_X;
this.dragRefOffsetX += this.FIX_VP_X;
this.offsetY -= this.FIX_VP_Y;
this.dragRefOffsetY += this.FIX_VP_Y;
this.itemMove(index, index + this.row + 1);
}

// 向右上滑
upperRight(index: number): void {
if (!this.isDraggable(index - (this.row - 1))) {
return;
}
this.offsetX -= this.FIX_VP_X;
this.dragRefOffsetX += this.FIX_VP_X;
this.offsetY += this.FIX_VP_Y;
this.dragRefOffsetY -= this.FIX_VP_Y;
this.itemMove(index, index - (this.row - 1));
}

// 向左下滑
lowerLeft(index: number): void {
if (!this.isDraggable(index + (this.row - 1))) {
return;
}
this.offsetX += this.FIX_VP_X;
this.dragRefOffsetX -= this.FIX_VP_X;
this.offsetY -= this.FIX_VP_Y;
this.dragRefOffsetY += this.FIX_VP_Y;
this.itemMove(index, index + (this.row - 1));
}

// 向左上滑
upperLeft(index: number): void {
if (!this.isDraggable(index - (this.row + 1))) {
return;
}
this.offsetX += this.FIX_VP_X;
this.dragRefOffsetX -= this.FIX_VP_X;
this.offsetY += this.FIX_VP_Y;
this.dragRefOffsetY -= this.FIX_VP_Y;
this.itemMove(index, index - (this.row + 1));
}

// 通过元素的索引，控制对应元素是否能移动排序
isDraggable(index: number): boolean {
console.info(index: ${index});
return index > -1; // 恒成立，所有元素均可移动排序
}

build() {
Column() {
Grid() {
ForEach(this.numbers, (item: number) => {
GridItem() {
Text(item + '')
.fontSize(16)
.width('100%')
.textAlign(TextAlign.Center)
.height(100)
.borderRadius(10)
.backgroundColor(0xFFFFFF)
.shadow(this.scaleItem == item ? {
radius: 70,
color: '#15000000',
offsetX: 0,
offsetY: 0
} :
{
radius: 0,
color: '#15000000',
offsetX: 0,
offsetY: 0
})
.animation({ curve: Curve.Sharp, duration: 300 });
}
// 添加震动
.onTouch(() => {
})
.onAreaChange((oldVal, newVal) => {
// 多列
this.FIX_VP_X = Math.round(newVal.width as number);
this.FIX_VP_Y = Math.round(newVal.height as number);
console.info(oldVal:${JSON.stringify(oldVal)});
})
// 指定固定GridItem不响应事件
.hitTestBehavior(this.isDraggable(this.numbers.indexOf(item)) ? HitTestMode.Default : HitTestMode.None)
.scale({ x: this.scaleItem == item ? 1.05 : 1, y: this.scaleItem == item ? 1.05 : 1 })
.zIndex(this.dragItem == item ? 1 : 0)
.translate(this.dragItem == item ? { x: this.offsetX, y: this.offsetY } : { x: 0, y: 0 })
.padding(10)
.gesture(
GestureGroup(GestureMode.Sequence,
LongPressGesture({ repeat: true, duration: 50 })
.onAction((event?: GestureEvent) => {
console.info(event: ${event});
this.getUIContext().animateTo({ curve: Curve.Friction, duration: 300 }, () => {
this.scaleItem = item;
});
})
.onActionEnd(() => {
this.getUIContext().animateTo({ curve: Curve.Friction, duration: 300 }, () => {
this.scaleItem = -1;
});
}),
PanGesture({ fingers: 1, direction: null, distance: 0 })
.onActionStart(() => {
this.dragItem = item;
this.dragRefOffsetX = 0;
this.dragRefOffsetY = 0;
})
.onActionUpdate((event: GestureEvent) => {
this.offsetY = event.offsetY - this.dragRefOffsetY;
this.offsetX = event.offsetX - this.dragRefOffsetX;
console.info(移动过程中event.offsetY：${event.offsetY},
this.dragRefOffsetY: ${this.dragRefOffsetY}, this.offsetY: ${this.offsetY});
console.info(移动过程中event.offsetX：${event.offsetX},
this.dragRefOffsetX: ${this.dragRefOffsetX}, this.offsetX: ${this.offsetX});
this.getUIContext().animateTo({ curve: curves.interpolatingSpring(0, 1, 400, 38) }, () => {
let index = this.numbers.indexOf(this.dragItem);
console.info('index= ', index);
if (this.offsetY >= this.FIX_VP_Y / 2 &&
(this.offsetX <= this.FIX_VP_X / 2 && this.offsetX >= -this.FIX_VP_X / 2)
&& (index + this.row <= this.lastIndex)) {
// 向下滑
this.down(index);
} else if (this.offsetY <= -this.FIX_VP_Y / 2 &&
(this.offsetX <= this.FIX_VP_X / 2 && this.offsetX >= -this.FIX_VP_X / 2)
&& index - this.row >= 0) {
// 向上滑
this.up(index);
} else if (this.offsetX >= this.FIX_VP_X / 2 &&
(this.offsetY <= this.FIX_VP_Y / 2 && this.offsetY >= -this.FIX_VP_Y / 2)
&& !(((index - (this.row - 1)) % this.row == 0) || index == this.lastIndex)) {
// 向右滑
this.right(index);
} else if (this.offsetX <= -this.FIX_VP_X / 2 &&
(this.offsetY <= this.FIX_VP_Y / 2 && this.offsetY >= -this.FIX_VP_Y / 2)
&& !(index % this.row == 0)) {
// 向左滑
this.left(index);
} else if (this.offsetX >= this.FIX_VP_X / 2 && this.offsetY >= this.FIX_VP_Y / 2
&& ((index + this.row + 1 <= this.lastIndex && !((index - (this.row - 1)) % this.row == 0)) ||
!((index - (this.row - 1)) % this.row == 0))) {
// 向右下滑
this.lowerRight(index);
} else if (this.offsetX >= this.FIX_VP_X / 2 && this.offsetY <= -this.FIX_VP_Y / 2
&& !((index - this.row < 0) || ((index - (this.row - 1)) % this.row == 0))) {
// 向右上滑
this.upperRight(index);
} else if (this.offsetX <= -this.FIX_VP_X / 2 && this.offsetY >= this.FIX_VP_Y / 2
&& (!(index % this.row == 0) && (index + (this.row - 1) <= this.lastIndex))) {
// 向左下滑
this.lowerLeft(index);
} else if (this.offsetX <= -this.FIX_VP_X / 2 && this.offsetY <= -this.FIX_VP_Y / 2
&& !((index <= this.row - 1) || (index % this.row == 0))) {
// 向左上滑
this.upperLeft(index);
} else if (this.offsetX >= this.FIX_VP_X / 2 && this.offsetY >= this.FIX_VP_Y / 2
&& (index == this.lastIndex)) {
// 向右下滑(右下角为空)
this.down2(index);
}
});
})
.onActionEnd(() => {
this.getUIContext().animateTo({ curve: curves.interpolatingSpring(0, 1, 400, 38) }, () => {
this.dragItem = -1;
});
this.getUIContext().animateTo({
curve: curves.interpolatingSpring(14, 1, 170, 17), delay: 150
}, () => {
this.scaleItem = -1;
});
})
)
.onCancel(() => {
this.getUIContext().animateTo({ curve: curves.interpolatingSpring(0, 1, 400, 38) }, () => {
this.dragItem = -1;
});
this.getUIContext().animateTo({
curve: curves.interpolatingSpring(14, 1, 170, 17)
}, () => {
this.scaleItem = -1;
});
})
);
}, (item: number) => item.toString());
}
.width('90%')
.editMode(true)
.scrollBar(BarState.Off)
// 多列
.columnsTemplate(this.str);
}
.expandSafeArea([SafeAreaType.SYSTEM], [SafeAreaEdge.TOP, SafeAreaEdge.BOTTOM])
.width('100%').height('100%').backgroundColor('#f1f3f5').padding({ top: 5 });
}
}
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