liver-push组件用snapshot 拍照，所得图片尺寸跟画面不一致

参考代码

                <live-pusher  
                    id="livePusher"  
                    ref="livePusher"  
                    class="livePusher"  
                    mode="FHD"  
                    :aspect="aspect"  
                    device-position="back"  
                    :auto-focus="true"  
                    :muted="true"  
                    :background-mute="true"  
                    :enable-mic="false"  
                    :style="{   
                        width: '750px',   
                        height: '750px'  
                    }"  
                    @touchstart="handleFocusIos"  
                />

snapshot所得图片 是黑屏 知道回事吗