Android TextView SetText A deep reason for Kaka

Recently found in the company project inside the ListView TextView is very time-consuming to call the SetText function, it was a little unbelievable, because if you set TextView to Wrap_content, then each call to SetText will be called to

........ 40334034            if (mmovement! = null) {4035                mmovement.initialize (This, (spannable) text); 40364037                /*4038                 * Initializing the movement method would have a set the4039                 * selection, so reset mselectionmoved to keep that from4040
   
    * interfering with the normal on-focus selection-setting.4041                 */4042                if (meditor! = null) meditor.mselectionmoved = false;4043            }4044        }40454046        if (mlayout! = null) {
   

                This function is very important 4047            checkforrelayout (); 4048        }40494050        sendontextchanged (text, 0, Oldlen, textLength); 4051        ontextchanged (text, 0, Oldlen, textLength); 40524053        notifyviewaccessibilitystatechangedifneeded ( Accessibilityevent.content_change_type_text); 4054

.........

The Checkforrelayout function, which re-starts layout based on how much text is

6807 private void More ... checkforrelayout () {6808//If We have a fixed width, we can just swap in a new text L ayout6809//If the text height stays the same or if the view height is fixed.68106811 if (mlayoutparams.wi DTH! = Layoutparams.wrap_content | | 6812 (Mmaxwidthmode = = Mminwidthmode && mmaxwidth = = mminwidth)) &&6813 (mHi NT = = NULL | | Mhintlayout = null) &&6814 (Mright-mleft-getcompoundpaddingleft ()-Getcompoundpaddingright () > 0) {6815//Static width, so try making a new text layout.68166817 int oldht = Mlayout.getheig HT (); 6818 int want = Mlayout.getwidth (); 6819 int hintwant = Mhintlayout = null?  0:mhintlayout.getwidth (); 68206821/*6822 * No need to bring the text in view, since the size is not6823 * Changing (unless we do the requestlayout (), in which case it6824 * would happen aT measure). 6825 */6826 makenewlayout (Want, Hintwant, unknown_boring, unknown_boring,6827 Mright-mleft-getcompoundpaddingleft ()-Getcompoundpaddingright (), 6828 false);  68296830 if (mellipsize! = TextUtils.TruncateAt.MARQUEE) {6831//In a fixed-height view, so use                    Our new text layout.6832 if (mlayoutparams.height! = layoutparams.wrap_content &&6833 Mlayoutparams.height! = layoutparams.match_parent) {6834 invalidate (); 6835 re  turn;6836}68376838//Dynamic height, but height has stayed the same,6839// So with our new text layout.6840 if (mlayout.getheight () = = Oldht &&6841 (mhintl Ayout = = NULL | |                Mhintlayout.getheight () = = Oldht)) {6842 invalidate (); 6843 return;6844 }6845            }68466847//We lose:the height has changed and we have a dynamic height.6848//Reques T a new view layout using our new text layout.6849 requestlayout (); 6850 invalidate (); 6851} E LSE {6852//Dynamic width, so we had no choice but to request a new6853//view layout with a new    Text layout.6854 nulllayouts (); 6855 requestlayout (); 6856 invalidate (); 6857}6858 }

The note has been written very clearly, so the width is set to a number or match_parent can make the settext time to shorten, that is.

Android TextView SetText A deep reason for Kaka